Flexible and printable electrooptic devices

ABSTRACT

This invention discloses how electrooptic devices including electrochromic devices that can be fabricated as tags or labels; and further the materials used, device structures and how these can be processed by printing technologies and on flexible substrates. In addition, systems using displays of such devices and their integration with other components are described for forming labels and tags, etc, that may be actuated wirelessly or powered with low voltage and low capacity batteries.

RELATED APPLICATION/CLAIM OF PRIORITY

This application is a national stage application under 35 U.S.C. §371of, and claims priority from, International Application No.PCT/US09/49644, filed 2 Jul. 2009, which is a PCT Application and isrelated to and claims priority of provisional application Ser. Nos.61/078,328, filed on Jul. 3, 2008; 61/087,796, filed Aug. 11, 2008;61/109,691 filed on Oct. 30, 2008; 61/156,932 filed on Mar. 3, 2009,61/168,421 filed on Apr. 10, 2009 and 61/187,619 filed Jun. 16, 2009,and PCT application PCT/US09/49644 filed on Jul. 2, 2009, all of whichapplications are incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to novel electrochromic materials, anddevices formed by these materials and the applications of theseelectrochromic devices. Particularly preferred applications of thesedevices, are in the area of flexible displays and/or those where theseare processed by printing methods. These displays are usually assembledor processed so that these are part of other electronic flexible and/orprinted products such as electronic labels and tags. This invention alsodiscloses electronic biodegradable labels and tags.

BACKGROUND OF THE INVENTION

Electrooptic devices which change their optical state/displayedinformation upon application of voltage, such as electrochromic (EC)devices, can be used for a variety of applications, for exampleautomotive mirrors, energy efficient glazing, displays, eye-wear andoptical filters, to name a few. The device construction and thematerials used have to be adapted to each application so that the deviceperformance is most suitable for the intended application. An emergingarea for EC applications are displays with wide ranging attributes andcost structures. As an example for use in displays, this technology isbeing developed for those applications where the tablet or the screen isrefreshed at video speeds or able to exhibit color images. In suchapplications, reversibility and rapid change of color is required. Anadvantage of EC displays is their wide viewing angle and the visibilityis not impaired under bright lights. On the other side of the spectrum,highly inexpensive displays and indicators are required that may beproduced for product labels and tags which are disposable or replacedperiodically. These displays may require irreversible information to bedisplayed or have limited cyclability. Irreversible means that thedisplay or the indicator change the state or show the information whenthey are activated the first time. Limited cyclability is usually about10,000 cycles or less. This information may fade away after a fewseconds or may last a long time giving permanence to the image (bistablestate). Further, many of the tags and labels for such uses may not havean onboard power source and thus may have to be activated by powerderived from other components located on the same tag or the label. Suchpower may be derived from a radio frequency coupling of an antenna onthe tag, an optical coupling with a source or ambient light, mechanicalcoupling to a motion or vibration, or a sonar source, etc. In all casesthe power to activate the display is limited. Since EC devices are ableto react at low potentials (typically less than 3V), power is not lostin upconverting the voltage. To meet a demand for many of the emergingdisplay applications, new materials, or new ways of using the existingmaterials is required. In addition, these displays and their integrationinto labels and tags should be done so that they can be produced at lowcost. Some of the low cost processing methods are use of printingprocesses, particularly high speed processes such as roll to rollprocesses for flexible substrates or continuous process to print onrigid substrates. The materials and concepts discussed here may be usedfor any EC application, but as demonstrated in several examples thesewould be particularly suitable for low cost displays. Since thesedisplays comprise several layers of different materials, printing meansthat at least one of the layers is deposited using printing methods.Typically at least one of the electrodes or an electrolyte is printed.In particular, materials and material combinations that change theiroptical state by polymerization and their use in the EC devices will bedisclosed. In addition, the metal layers when formed or removed alsoresult in high contrast. Use of these materials will also be disclosed.EC device structures, processes to fabricate these devices and theirintegration with other components at a systems level for manufacturingof complete labels and tags along with their applications will bedisclosed.

SUMMARY OF THE PRESENT INVENTION

In accordance with the purposes of the present invention, as embodiedand broadly described herein, the invention provides materials, methodsof forming and applications of electrochromic devices. These methods canbe advantageously used to form displays which can be made at low costfor many applications such as labels and tags.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Shows the schematic of the structure of an EC device formedusing this invention;

FIG. 2: Shows the schematics of the structure of another EC deviceformed using this invention;

FIG. 3 a: Shows schematics of an EC device fabricated by the inventivemethod;

FIG. 3 b: Shows schematics of an EC device (top and front view)fabricated by the inventive method;

FIG. 3 c: Shows schematics of an EC device fabricated by the inventivemethod;

FIG. 4: Shows schematics of an EC device fabricated by the inventivemethod;

FIG. 5: Shows schematics of an EC device fabricated by the inventivemethod;

FIG. 6 a Shows schematics of an EC device fabricated by the inventivemethod;

FIG. 6 b Shows schematics of an EC device fabricated by the inventivemethod;

FIG. 7 Shows schematics of an EC device fabricated by the inventivemethod;

FIG. 8 Shows schematics of an EC device fabricated by the inventivemethod;

FIG. 9 Schematics of a two electrode interdigited display patternshowing characters.

FIG. 10 Shows schematics of a device with electrolyte in channels;

FIG. 11 Shows a transmission change of an EC device when colored andbleached

FIG. 12 Shows schematics of layout of a display and other components ona tag or a label;

FIG. 13 Shows cross-section of a display that may be used as a label ora tag;

FIG. 14: Shows a schematics of a label or a tag that uses severalindicators;

FIG. 15: Shows cross-section of a display that may be used as a label ora tag;

FIG. 16: Shows cross-section of a display that may be used as a label ora tag;

FIG. 17: Schematics of electrodes for electrooptic device andconnections scheme to various tag components on a substrate;

FIG. 18: Schematics of integration of various components on the tagsubstrate shown in FIG. 17;

FIG. 19: Schematics of various components on the tag substrate shown inFIG. 18;

FIG. 20 a: Schematics of various components on the tag substrate shownin FIG. 18, top view;

FIG. 20 b: Schematics of various components on the tag substrate shownin FIG. 18, bottom view;

FIG. 21 a-c: Schematics of the electronics component used for theassembly in FIG. 18;

FIG. 22: Schematics of connections for placement of an electroopticdevice and connections scheme to various tag components on a substrate;

FIG. 23: Schematics of the electrode and partial connection scheme foran electrooptic device to be connected to the tag shown in FIG. 22.

FIG. 24 a-d: Schematics of formation of the electrooptic device to beconnected to the tag shown in FIG. 22.

FIG. 25 a,b: Schematics of an overview of the display element from FIG.24 integrated with the tag substrate of FIG. 22, top and bottom views.

FIG. 26 a,b: Schematics showing details of connections and components ofthe display element from FIG. 24 integrated with the tag substrate ofFIG. 22, top and bottom views

FIG. 27: Shows a card incorporating display according to the invention;

FIGS. 28 a-f: Schematics of an indicative device and a processingsequence for its formation;

FIG. 29: Shows a schematics of a system that uses a display;

FIG. 30: Shows a schematics of a system that uses a display;

FIG. 31: Schematics of a wireless powered display system constructedusing this invention.

DETAILED DESCRIPTION

This invention discloses fabrication of low cost, low powerelectrochromic displays and their applications in integrating them in avariety of ways. Although the invention illustrates most of the noveltyusing EC materials and devices, however, in some cases otherelectrooptic materials and technologies, such as liquid crystals,electrophoretic and others may also be used. In particular, theapplications targeted are tickets (for events, games, transportation,lotteries etc.), tags, labels, etc. that can be used as product labels,supermarket shelf price labels, security labels, cards (e.g., giftcards, other limited use greeting cards, credit and debit cards),medical applications such as status of a patch or a wound, etc. Theselabels may be used for office products such as to label documents,folders, binders, etc. One may activate these products wirelessly, anddepending on the user selectivity, displays on specific office productsmay be activated which may be easy to identify visually for the task athand. All of these applications are collectively called as “tags andlabels”. These labels may comprise of integrated sensors, or a sensorfeed may be provided to them. These sensors may be looking at/forchanges in type or value of pH, color, optical absorption, fluorescence,weight, permeability, moisture, electrical resistance, capacitance,impedance, mechanical modulus, magnetic susceptibility, volume, time,temperature, pressure, gas, enzymes, other chemicals, etc. Thesedisplays may be irreversible, that is, once activated they can form animage which stays there for a period of time, which may be consideredpermanent relative to the product life. As an example, for inventorycontrol, an area on the label applied to the product package may changecolor via a stimulus when it is close to expiration. Such a product canthen be easily identified by the store personnel and removed. In somecases, the label should be reversible so that the image can be updatedperiodically and some may even require holding the image without furtherpower consumption. An example of this may be a price label on thesupermarket shelf. Applications such as cards (bus or train passes,school lunch cards, store gift cards, etc.) may have a display that isperiodically updated when one takes them near an emitting source, andthen the image needs to be retained without power until the card is usednext or for any desired time. Thus there are many examples wherewireless communication such as by optical, sonar or radio frequencycommunication, will energize these displays and the associatedelectronics. The power may also come from onboard sources such as abattery or solar cell. Although the preferred mode is wirelessactivation, this invention may also be used with wired displays.Examples of these applications and some of the devices suggested forthese may be found in U.S. Pat. No. 7,286,061 (conditional access forantitheft of optical media) and patent applications UA20080111675(observable properties triggered upon interrogation of RFIDs fortracking systems); UA20080100455 (a tag with an antenna and a chipshowing a persistent image after interrogation for inventory control);UA20080170287 (a security device to provide a visual alert);UA20070114621 (wirelessly powered flexible tag); UA20070114365(antitheft optical shutter activated by RF); PCT applications WO08022972(EC indicator for product authentication) and WO08022966 (EC indicator).Printing of several components on flexible substrates including displaysor indicators along with connectors, sensors, logic and powerelectronics on a substrate to reduce cost is commonly known theme asincluded in many publications, e.g. a few examples are Aperturen 2005publication from Acreo AB (located in Krista, Sweden)(http://www.acreo.se/upload/Publications/Aperturen/Aperturen2005-02.pdf),US patent applications UA2007/0143774, UA2007/0128760 and PCTapplication WO08/115591. All of these also anticipate a common layer ormaterial that is common to several components. However, none of theseaddress the issue of biodegradation or matching the mechanicalproperties of the various layers so that flexible devices with highdurability can be obtained. Flexibility usually refers to products madeon stock (or substrate) that is processed in a roll to rollconfiguration where the stock has to be flexed around the rollers in theprocessing equipment, or where flexibility or bending is needed from theproduct during its use.

Specifically, in a variety of consumer and industrial products/processesthat are using radio frequency (RF) wireless technology to readinformation on tags or labels on product packaging, passports, paymentcards, inventory control, product tracking, animal control, etc. Thesetags comprise of an antenna coupled to a radio frequency chip. When thistag is wirelessly coupled by radio frequency via an authorized source,the chip on the tag is energized and the information stored on this chipmay be read. The emitter or the source is usually a part of the networkand can wirelessly communicate with the chip. In the emergingapplications the RF chips may have an added functionality where thechips are further connected to additional devices to activate an actionfrom the power derived from the antenna energization. This could be adisplay, a sound buzzer, or a mechanical lock, etc. Many suchapplications have been described in the patent literature, such as USpatent applications 2007/0,114,621; 2008/0,100,455; and U.S. Pat. Nos.7,227,445; 7,273,181. The wireless coupling to the chip via the antennaon the tag can also provide power to turn on the display (passive).Alternatively, a battery on the tag (active) may be used to accomplishthis. However, in some cases the latter approach may make the productmore expensive and disposal may be an issue, thus passive approach ispreferred. Alternatively wireless energy harvesting devices, such as asolar cell may be located on the tag which may also be formed by aprinting process. Other wireless power devices that can be used harvestpower from vibrations, sound, RF power, etc. Some of the emergingdevices based on these principles are from Adaptive Energy (Hampton,Va.) that uses a piezoelectric sensor to convert power from vibrations,or from Powercast (Pittsburgh, Pa.) that uses a sensor for powerharvesting from RF radiation. These devices may interface with batteriesto recharge them, or charge a capacitor. One may be print specificcomponents, such as the capacitor, battery or even the entire powerharvesting system. Depending upon a desired response based on thedialogue between the chip and the interrogating source, the display maybe energized. Since this coupling may last for a few seconds, in somecases it is desired for the display to be persistent or show theinformation for a long time without consuming power. As an example,cafeteria food card, store gift card, train or bus card may show theamount remaining when one swipes the card in a reader or walks by abooth with an emitting source for wirelessly coupling to the card (i.e.,the antenna and the chip on the card). This information may have toremain displayed for a few seconds for some applications while forothers it should be displayed for several days or weeks. This action mayalso require erasure or updating of any past information that is beingdisplayed. A label on a package at a store checkout can interactwirelessly with the terminal, which can then communicate through anetwork to verify the product authenticity, and turn on an EC indicatorpermanently. In another application on inventory control, a wirelesscommunication system in a supermarket can interact with any of thedesired or all of the product labels on the product package, and thenturn an indicator on the package label if it is expired, or is recalled,or needs to go on sale, etc. The information on the display has toremain on for sufficiently long so that the store employees are able toget to them and take proper action. Thus, these labels have to be lowcost so as not to excessively increase the cost of products, tags, etc.Further, the display materials and processes used have to be compatiblewith packaging materials and systems and be non-toxic to the environmentwhen disposed. Many of the preferred electrolytic compositionscomprising ionic liquids do not interact with common packaging materialssuch as paper, polyvinyl chloride, polystyrene, polycarbonate,polyester, acrylic and polyolefins and do not vaporize. It is alsopreferred that one is able to use polymeric materials as coatings orsubstrates or as part of active devices that decompose in the landfillsor in an industrial compostable facility. This is important as suchproducts will be made and disposed in large numbers. The materials thatbiodegrade in soils are those that show substantial degradation within180 days in a land fill. Example of the materials (for clear or opaquesubstrates or other layers as described in this disclosure) that arebiodegradable are conventional polymers with additives that make thesebiodegradable (e.g., see Eco-Pure™ additives that promotebiodegradability in polymers when added in a concentration of about 1%,available from Biotech Environmental LLC in Albuquerque, N. Mex.) orthose polymers that biodegrade themselves. Polymers for the formercategory are polyethylene, polypropylene, polyester, polystyrene,polycarbonate, and many others including addition to any layer in thedevice. Examples of the latter category are polylactic acid basedpolymers which includes various crystallinity grades varied by changingthe proportion of D and L lactic acid units (e.g. sold by NatureworksLLC, Minnetonka, Minn.), polyhydroxyalkanoate, poly-ecaprolactone, andpolyesters such as poly(butylene adipate terephthalate) (sold as Ecoflexfrom BASF, Germany). Examples of additives to promote biodegradation ina variety of polymers are provided in published US patent application20080103232, which is included herein by reference. More onbiodegradability requirements and regulatory standards is contained inmany standards such as ASTM D5338, ASTM D6400, ISO 14855, ISO 16929, ISO17088, ISO 20200 and EN 13432 (European Norm). Biodegradability for thepurposes of this disclosure is defined as a material meeting any of theabove regulatory standards. It is preferred that the biodegradablematerials meet at least one of these standards. In some cases the selfbiodegradable polymers may have high permeability to moisture. These maybe coated with polyolefins, wherein these polyolefins may comprisebiodegradation promoting additives. Those polymers derived from bio feedstock may also be used (e.g., polyols used in polyesters and urethaneswhich are derived from plants and seeds such as corn, soyabean, castor,linseed), however, the preferred materials are those that biodegraderegardless of their source. Paper includes cardboard, fabrics, or otherpaper-like structures such as mats, non-woven webs, etc which includesnatural and manmade polymers including those that biodegrade. Even thesematerials could be made to biodegrade faster in specific landfillenvironments when additives such as those described above are added.

It is important to realize that the substrates used for printed andflexible displays, not only house the display but also the electronicsincluding antennas if used. Thus the biodegradation is an importanttopic for the entire flexible and/or printed electronic labels and tagswhich would be made in large numbers and disposed. These includeelectronic RFID tags and labels. If flexible and/or printed electronicsis going to be produced in large quantities and then disposed, then theentire product or most of it needs to be biodegradable. As an exampleflexible solar cells and many products need to be stable tophotodegradation but then biodegrade when disposed. One can use theabove principles of making biodegradable products for any printed and/orflexible electronics product even if it does not have a display. Alsoencapsulation layers, connectors, antennas, sealing adhesives, all ofthe layers that use polymers can be made of biodegradable matrices oradditives added to do so. This can be done for both thermosets andthermoplastics. There may be minor components and coatings that may notdegrade readily, but preferably more than 50% weight of the product andmore preferably more than 80% weight of the product and most preferablygreater than 98% of the product weight of flexible and/or printedelectronics can be designed to biodegrade. This would be a better optionas compared to recyclability due to the difficulty of disassembly ofvarious materials as many of these are present as coatings andadhesives. Since biodegradation usually kicks in landfills where thereare microbes present, some of the materials may be optionally recycledif they are not disposed in the landfill. One may use these principlesof using additives for substrates and other layers for electrooptic (EO)devices that may use polymeric substrates and polymeric layers includingelectrolytes, adhesives and conductors. Some examples of products thatcan be made biodegradable are EC windows and EC automotive mirrors (seePCT application serial number PCT/US09/32491 filed on Jan. 29, 2009,which is included herein by reference), non-emissive polymeric displaysfor electronic books and readers, electronic billboards, light emittingdiodes for lighting and displays, flexible solar cells,electroluminescent displays, etc.

Since the indicators and displays of this invention may be printed, theymay also be printed on the surface of any product whether it isconductive or nonconductive without making a separate label. They can beused for labels and indicators for a wide variety of consumer productsand packages and are durable in performance. Further, for those labelswhere the power source is only RF activation, the displays have tofunction under low power environments where both the voltage and thecurrent output of the chips on the tags are limited. These displaysshould be preferably energized at lower than 5V, preferably lower than2.5 V. The average current consumed should be less than 20 mA,preferably lower than 3 mA during the period in which the displays arepowered. Further, it is also preferred that the displays be powered inless than 10 s, and preferably in less than 2 s. The persistence time(i.e., the time for which the information is displayed after the poweris removed) may be tunable based on the composition of the electrolyteor the electrode from about a few seconds to forever. Forever orpermanent is always relative to the product/package life. Typically,this is from weeks to several years. If electrochromic displays are usedthat are part of an active matrix pixel system, then it is preferredthat the threshold voltage be below 1.5V, so that power can betransmitted below this voltage to the pixels without activating theconnectors.

Display Materials and Devices

The EC display devices may comprise of several layers, sometimes the ECmaterial (or electrooptic material) is located on an electrode as aseparate layer from the electrolyte, and sometimes EC material may beboth in the electrolyte and in additional layers, and yet in other casesit may solely reside in the electrolyte. Since one of the primaryobjective of the invention is low cost products, it is preferred toreduce the number of layers in an EC device, thus those EC devices wherethe EC material is resident only in electrolytes and additionalelectrochemically active layers are not used and are most preferreddevice constructions. Redox materials/species are those that undergoelectrochemical oxidation and reduction upon device activation, andthese may be reversible or irreversible. Cathodic redox undergoreduction at the cathode and the anodic redox undergo oxidation at theanode. In addition, it is preferred that all of the layers are printedsequentially until the device is complete.

The electrolytes that are deposited by printing should become solidafter deposition. This may be due to the removal of a solvent, coolingor by further reaction (e.g. polymerization and/or crosslinking). Theelectrolytes may be hydrophilic or hydrophobic (latter are preferred).For hydrophilic electrolytes those systems are preferred where thedevice performance is not dependent too much on water content, otherwisethe performance of this device will change when subjected to differentenvironmental conditions.

One method to create the EC displays with long persistence or permanentimage is by using those materials as redox agents that become coloredupon polymerization. These are particularly suitable for thoseapplications where only a single activation or a permanent change isrequired. Many polymers are conjugated and hence deeply colored, whereas their monomers are not. The literature is replete with examples wheresuch polymer coatings are formed on conductive electrodes byelectrochemical or chemical methods. These coatings are then used in ECdevices which are reduced and oxidized reversibly to change their color.However, those EC devices are not described where such polymer is formedonly when the device is activated. This results in coloration (or animage if the electrode is patterned such as in a display or anindicator) when the device is powered. The device is assembled withmonomer in the electrolyte and, upon powering, the monomer polymerizes(electro-polymerization) at one of the electrodes resulting in a coloredspecies. If this coating has a reasonably good adhesion to theelectrode, the image does not smudge with time due to the migration ofthe colored species. PCT application WO 2006/008776 describes additionof oligomers (all polymerizable materials are considered as monomers inthis patent application) of conductive polymers and polymers to theelectrolyte for faster transport of electronic charges, but do notcontemplate a redox activity where polymerization at an electrode isinvolved. Persistent or stable EC devices are also described in USpatent applications 2008/0204850 and 2007/0139756. However, thesedevices predominantly use a vapor deposited metal layer that is oxidizedupon device activation which were deposited on optical media (e.g., CDsand DVDs) as shutters. This disclosure does not discuss how thetechnology can be used for labels and tags. These used both physicalvapor deposition (PVD) and wet chemical processing to form the devices.Such technologies are difficult to practice on low cost flexiblesubstrates which need to be processed in a roll to roll fashion. Inaddition, all of these devices changed from a dark to a clear state, andwere sensitive to moisture. The devices of the current disclosure avoidthese limitations, i.e., they can be formed without using PVD at theconvertors facility, can be deposited on flexible substrates, roll toroll processes may be used, can change from clear to dark, and alsohydrophobic electrochromic materials and electrolytes may be used tomake these less sensitive to moisture. For all these reasons the currentdisclosures here are more suitable for use in displays particularly tomake tags and labels.

There are many materials that can be electro-polymerized from colorlessor faintly colored monomers to deeply colored polymers that absorb allor part of the visible radiation. Some of these electrochemically activepolymers useful in the instant invention include (which can bepolymerized from their monomers present in the electrolyte), withoutlimitation, polyphenylene vinylenes, polythienylene vinylenes,polyalkoxythienylene vinylenes, polyfurylene vinylenes, polythiophenes,polyisothianaphthenes, polyanilines, polyarylamines, polyindoles,polypyrroles, polyalkoxyphenylenes, polyphenylenes,polyperinaphthalenes, polynaphthylamines, polyvinylmetalocenes, polymersof heteroaryls linked to metals (e.g. see US patent application2007/0191576), carbon cluster (fullerenes) and carbon cluster containingpolymers, polyimides, polyviologens. Other electrochemically activepolymeric materials which may be employed in the present inventioninclude, without limitation, derivatives of the aforementioned polymers,such as those prepared by sulfonation or substitution, copolymers (froma mixture of monomers), blends and composites, where the matrix may beorganic or inorganic but at least one of the components is from thepolymers or their derivatives described above. Further, depending on thespecific monomer one can obtain different colors. Thus multicoloredimages and displays may be formed. A simplified device schematic isshown in FIG. 1. An electrolyte 12 is placed touching two conductors 10and 13. The conductors are usually coatings on substrates, or one ofthem may be a metal foil. The electrolyte comprises of a monomer as aredox agent, e.g., thiophene derivatives such as3,4-Ethylenedioxythiophene, 2-2′bithiophene, 2-3′bithiophene, 3butylthiophene, 3-4 dimethylthiophene, terthiophene. It is preferredthat the monomer be a salt or have a boiling point above 100° C.,preferably above 150° C. so that its loss by evaporation with time (orduring processing) is low in order to keep the device performance.Examples of monomers with salt like structures that result in conductivepolymers are several that can be electrochemically polymerized. Forexample, anionic salts of thiophene can be used for this purpose (seeGiumanini, A. G. et al, J. Organic Chemistry, vol 41(12), p-2187-2193(1976)). In this example, the cation is an ammonium moiety to which thethiophenes are attached. The anions can be halide groups, or the onesdescribed for the ionic liquids in this invention and are the same asthe anion of the ionic liquid in the formulation. A specific example isammoniumtrimethyl-3-thenyliodide as shown below. Various derivativessuch as different alkyl groups on the thiophene or on the nitrogen maybe attached to change the redox and or coloration properties.

The electrolyte may also comprise of other materials such assolubilizing medium and addition of ion conductive salt. One may alsouse an ionic liquid which fulfills the role of both a solubilizingmedium and a salt. When power is applied across the two conductors,bithiophene (a colorless material) polymerizes at the anode due to theoxidation into a reddish colored material. This material is usually notsoluble in the electrolytic medium and adheres to the anode. With timethis layer may further oxidize or reduce and may again change color.Changing the type of redox species or using a mixture of redox species,e.g., more than one anodically polymerizing monomers and/or more thanone cathodic material may be used in the same device to control color.The color may be imparted due to the two or more different colors ofpolymers or copolymers produced when the device is activated, or at onevoltage first color film is deposited and at other voltages a second orthird color film is deposited and this composite film comprising ofvarious color films exhibits different color as compared to thecomponent films. As an example, polymerization of 3-methyl thiopheneresults in a red colored polymer, polymerization of3,4-ethylenedioxythiophene results in a blue colored polymer andpolymerization of2,3-di(thien-3-yl)-5,7-di(thien-2-yl)thieno[3,4-]pyrazine results in agreen colored polymer (Gursel Sonmez, Clifton K. F. Shen, Yves Rubin,and Fred Wudl, Angewandte Chemie (2004), vol 116, p-1524-1528). Thesematerials may be used to form the EC devices of this invention, in theexamples provided later a few additional thiophenes are examined thatprovide other colors. The electrolyte may have other ingredients whichare discussed in more detail later.

We have also discovered that for these devices to work rapidly at lowerpotentials the electrolyte, in addition to the electrochemicallypolymerizable monomer (or redox material 1), should preferably alsocomprise of a material (redox material 2) that can simultaneouslyundergo redox activity at the other (opposing) electrode within thepotential range of the device (complimentary redox material). Thismaterial may or may not possess EC properties. In those displays whereone is viewing the display from the side of 10 (anode), and theelectrolyte is highly opaque, it does not matter if the reaction of thecathode (13) produces color. As an example, with bithiophene (whichpolymerizes at the anode) one can use a viologen salt or anthraquinonein the electrolyte as a cathodic material. Alternatively, if thepolymerization is cathodic, e.g., polymerization of another thiophenederivative 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDT), then one canuse anodic redox material in the electrolyte. Some examples of anodicredox materials are ferrocene, phenothiazine, phenazine,tetrathiafulvalene and aromatic amines to name a few. There are hundredsof variations and derivatives of the anodic and the cathodic redoxmaterials. More examples of these may be found in US patent application2002/0012155, U.S. Pat. Nos. 6,016,215; 6,496,294; 5,239,405; 5,140,455;7,064,212; 6,961,168. The electrolyte may comprise of more than onemonomer or/and more than one redox material for varying the color or thereactivity. The cathodic material may also be monomeric that results ina conducting polymer formation at the anode. An example of anodicallypolymerizing thiophene isbis[cis-1,2-di(4-bromophenyl)-1,2-ethenedithiolene]nickel.

As will be discussed later, for reversible devices, one can usereversible dyes in the electrolyte rather than monomers that polymerizeon device activation, e.g., combinations of anodic and cathodic dyes.Several examples of these were described above. One may also add bridgeddyes where the anodic and cathodic dyes are covalently bonded to give asingle molecule. In this case it is preferred that either the cathodicdyes or the bridged dyes comprise of viologen (bipyridinium) moiety,since the viologens have high coloring efficiencies and result inintense coloration for a small amount of power that they consume.

Another way to construct such devices is shown in FIG. 2. Here if apolymer is formed anodically, then rather than using a cathodic materialin the electrolyte one may use a cathodic layer on the opposingelectrode. The conductive electrodes are 20 and 23, and the electrolyteis 22. The cathodic layer is 27. Cathodic layers may or may not have ECproperties, as long as they are capable of undergoing reduction or storethe appropriate ions (e.g., charge storage carbon layers ascounterelectrodes (opposing electrodes) are described in EC devices aredescribed in U.S. Pat. No. 6,118,573). Capacitive or redoxcounterelectrodes layers may be used in this or any other type of ECdevices described herein, if that function is not provided by a speciesin the electrolyte.

The cathodic layer does not have to be electrochromic, but it has toeither provide reactivity or provide a mechanism to store the cations,at least temporarily. Some examples are coatings comprising tungstenoxide, molybdenum oxide, PEDOT, e.g. Clevios™ available from HC Starck(Newton, Mass.), etc. Similarly, if the polymerization is cathodic, thenone may use anodic layers. After the device is activated once, thisdevice may be repeatedly cycled by powering and shorting or applying alow bleach potential so as to color and bleach the EC layer that isformed in the first cycle. This assumes that the polymerizationpotential is higher than the coloring and bleaching potential. This willprevent the same monomer to polymerize on the counterelectrode duringrepeated cycling, unless that is desired.

Displays may also be formed where the metals are either deposited toform the contrast, or the metals are selectively removed from the areasto generate contrast with the surroundings. The former is preferred, asit does not require a pre-deposition of the metal. Methods to removemetal in devices are provided in US patent applications 2007/0139756,provisional U.S. applications with Ser. Nos. 60/947,366 and 61/025,069filed respectively on Jun. 29, 2007 and Jan. 31, 2008, which are allincluded herein by reference. In this case a metal layer is deposited onone of the electrodes before assembling the device. The electrolytecomprises of a redox or an ion conductive material that can eitheroxidize the metal to a different optical state or remove the metal asions and transport then through the electrolyte for redeposition on theother electrode. In the first case the reaction is largely irreversible,and in the second case depending on the ingredients used in theelectrolyte and the metal choice it may be reversed. Deposition ofmetals is known for reversible display and other EC devices, someexamples are U.S. Pat. Nos. 5,056,899; 6,552,843; 6,111,685. Anadvantage of metal deposition is their stability towards UV. Thus animage formed in this way can be quite stable to outdoor exposure.

There are several ways of forming devices with metal deposition, andparticularly suitable for printed displays and also those where theimage may be permanent or reversible. As an example one may form thisdevice as schematically outlined in FIG. 1, with an electrolyte 12sandwiched between the two conductors 10 and 13. Preferred electrolytesare hydrophobic so that these are not impacted by ambient conditions. Anexample of this is provided in U.S. Pat. No. 6,862,125, where ahydrophobic ionic liquid such as N-butyl-N-methylpyrrolidiniumbis(trifluoromethylsulfonyl)imide (BMPNTF) is used with EC materialswhich are metal salt and an anodic compound. For example, the preferredmetal salts are those that have the same anion as the ionic liquid.Preferred metals are aluminum, silicon, germanium, selenium, indium,tin, antimony, tellurium, bismuth, titanium, vanadium, chromium,manganese, iron, cobalt, nickel, copper, zinc, silver, gold, tungsten,lanthanum, cerium, praseodymium, neodymium, samarium, europium,gadolinium, terbium, dysprosium, holmium, erbium, yttrium, magnesium,calcium and mixtures thereof. For example, some of salts of thesecompatible with BMPNTF are bismuth (III)bis(trifluoromethylsulfonyl)imide, zinc (II)bis(trifluoromethylsulfonyl)imide, iron (II)bis(trifluoromethylsulfonyl)imide. It is preferred that the electrolytealso comprise of an anodic material. Anodic materials are the same asdescribed above, i.e., ferrocene, phenothiazine, phenazine,tetrathiafulvalene and aromatic amines to name a few. However, one mayalso use an anodic material (monomer) that polymerizes for anirreversible system. For example, one may use bithiophene as anodicmaterial. In this case the metal plates on one electrode and bithiophenepolymerizes on the other. If the metal part of the display faces theuser, it will have high stability to UV in the activated or the coloredstate, as metals tend to have better UV resistance as compared topolymers.

Another example uses hydrophilic ionic liquids, such as those where theanion is chosen from halides (Cl, F, Br), nitrates, sulfates,thiocyanates and carboxylates. As an example one could use1-Methyl-3-octyl-imidazolium chloride and solubilize chloride metalsalts along with anodic species. One can also use ionic liquids withhigh melting points (50 to 150 C), but when these are mixed with metalsalts and/or other ionic liquids, their melting point is lowered tobelow room temperature. Two or more ionic liquids mixed together mayalso form eutectics with melting points lower than the components (themixtures may have different cations and anions, or one of these may bethe same). For example 51 mole % of 1 ethyl-3-methylimidazoliumchloride, 6 mole % of N-methylpyrrolidinium chloride and 43 mole % ofsilver chloride is a liquid at room temperature (e.g., see U.S. Pat. No.6,552,843). Environmental friendly cations, such as choline, may also beused which form ionic liquids with a number of anions, e.g.,acesulfamates, thiocyanates, chlorides andbis(trifluoromethylsulfonyl)imide (NTF). Another example ofenvironmentally friendly ionic liquid is ethyl, methyl imidazoliumthiocyanate. The importance of using ionic liquids in these applicationsis to ensure that the mobile phase is always present and is not lost tothe environment. Since ionic liquids have negligible vapor pressure,these are not prone to evaporative losses as compared to non-ionicfluids. Further, use of aqueous based systems is also helpful duringprocessing where one does not have to use solvents which may be moretoxic. A preferred embodiment is where all the solvents and the redoxmaterials in the printable electrolyte are salts so that none of thesematerials have a tendency to leave the device upon long term storage.

One may produce an EC system which uses several electrolytes which havedifferent degrees of solubility of different electrochromic materials(e.g. varying hydropillicity to hydrophobic character). As an example ifthese EC materials have different colors, then the various electrolytesmay be printed in close proximity but without the fear of an EC materialdiffusion from one electrolyte to the other due to their limitedsolubility of the EC materials in adjacent areas or pixels. This meansthe electrolyte layer in a device is replaced by a number of discreteareas of various electrolytes.

Another type of device that may be formed by metal deposition is shownin FIG. 2. The metal deposition electrolyte 22 as described earlier mayalso be combined with an anodic layer 27 rather than an anodic materialadded to the electrolyte.

The electrolytes discussed for all of the devices above may have otheringredients such as UV stabilizers, inert salts, viscosity modifiers,surfactants, antifoaming agents, tackifiers, flowability modifiers,binders, opacifiers, adhesion promoters, fillers, colorants etc. Some ofthese additives will be described in more detail below. One may also addadditives to make the electrolyte biodegradable, so that it degradesrapidly once it is put in a landfill. The electrolyte may also havemonomers with or without catalysts that can be polymerized (includingcrosslinked) to solidify the layer. The layer may also be solidified byremoval of a solvent and or cooling (if deposited from a hot melt). Someof the preferred polymers that are used in the electrolyte matrix and donot participate in electrochemical activity when the EC device ispowered to generate color are polyurethanes, acrylics, epoxies,fluoropolymers, mixtures of these or monomers along with catalysts andinitiators used to form these polymers. Typically if formed polymers areused then solvents are used in the composition to deposit theelectrolyte layer then this solvent is then removed after deposition,and if monomers are used they are polymerized after the layer isdeposited. The nature of all these ingredients will depend on theircompatibility with the basic electrolyte composition. The electrolytecomposition where the EC activity is within the electrolyte comprises ECmaterials (i.e., redox species) along with a solubilizing medium whichis typically a liquid plasticizer with a boiling point in excess of 200C (which may be ionic liquid). High boiling point ensures that theplasticizer does not vaporize readily over time. Ionic liquids arepreferred as these have negligible vapor pressure. The solvent that isremoved from the electrolyte composition after it is deposited,typically has a boiling point greater than 90° C. and preferably greaterthan 95° C. This is so that these compositions are not too unstableduring processing, i.e., if the solvent evaporates then the viscosity ofthe composition will change leading to process conditions which will notbe too stable. Some of the preferred solvents are propyl acetate, butylacetate, methyl sulfoxide, dimethylformamide, 1-methoxy-2-propanol anddiethyleneglycol monoethyl ether acetate.

Although many materials known to absorb ultraviolet radiation may beemployed herein, preferred ultraviolet stabilizing agents inelectrolytes and other EC layers include “UVINUL” 400[2,4-dihydroxy-benzophenone (manufactured by BASF Corp., Wyandotte,Mich.)], “UVINUL” D 49 [2,2′-dihydroxy-4,4′-dimethoxybenzophenone (BASFCorp.)], “UVINUL” N 35 [ethyl-2-cyano-3,3-diphenylacrylate (BASFCorp.)], “UVINUL” N 539 [2-ethylhexyl-2-cyano-3,3′-diphenylacrylate(BASF Corp.)], “UVINUL” M 40 [2-hydroxy-4-methoxybenzophenone (BASFCorp.)], “UVINUL” M 408 [2-hydroxy-4-octoxybenzophenone (BASF Corp.)],“TINUVIN” P [2-(2′-hydroxy-5′-methylphenyl)-triazole] (Ciba Corporation,Tarrytown, N.Y.)], “TINUVIN” 327[2-(3′,5′-di-t-butyl-2′-hydroxyphenyl)-5-chloro-benzotriazole (CibaGeigy Corp.)], “TINUVIN” 328[2-(3′,5′-di-n-pentyl-2′-hydroxyphenyl)-benzotriazole (Ciba GeigyCorp.)] and “CYASORB UV” 24 [2,2′-dihydroxy-4-methoxy-benzophenone(manufactured by American Cyanamid Co., Wayne, N.J.)], with “UVINUL” M40, “UVINUL M” 408, “UVINUL” N 35 and “UVINUL” N 539, Bisbenzotriazolessuch as2,2′-methylene-bis[4-tert-octyl-6-(2H-benzotriazolyl-2-yl)phenol],TINUVINT™. 360; Asymmetrical bisbenzotriazoles substituted by aperfluoroalkyl moiety, e.g.,5-Trifluoromethyl-2-(2-hydroxy-3-(di-n-butylaminomethyl-5-tert-octylphenyl)-2H-;Tinuvin 928, CGL777 and CGL139 (all from Ciba). The ultravioletstabilizing agents when used in a by-weight range of about 0.1% to about15%, with about 2% to about 10% being preferred.

Solidification by polymerization or by multiphase process are welldescribed in U.S. Pat. Nos. 7,300,166 and 6,002,511 which are includedherein by reference. Electrolyte formulations may also comprise ofsolvent(s) that are removed by evaporation during processing. Ifmonomers are used for solidification, then these are different from theones present in the electrolyte that electropolymerize in the device togenerate color when electrically activated. These monomers are callednon-electroactive. The non-electroactive monomer amount (forsolidification) in these layers is typically less than 50% by weight ofthe total composition and more preferably less than 10% by weight. Anexample may be use of 2-hydroxy ethyl methacrylate (polyHEMA) withethylene glycol methacrylate as the crosslinker and an appropriatecatalyst, such as benzoyl peroxide, which are all dissolved in theelectrolyte (if curing by light such as UV is used, then one may employan appropriate photoinitiator, a number of these are available from CibaSpecialty Chemicals, White Plains N.Y.). If silicones are used one mayuse the platinum based chemistry for cross-linking these materials. Thispolymerization is conducted by heating after the electrolyte deposition.Polymers for the hydrophobic ionic liquids with fluorination may be morecompatible with fluorinated monomers such as tetrafluoromethylacrylate;1H,1H,7H,dodecafluoroheptyl methacrylate; and a variety of fluorinatedpolyethers. Functionalized fluoroethers are available from SolvaySolexis (Thorofare, N.J.) under the tradename of Fluorolink™. Anotherexample of a material is 8155 electroluminescent medium (from DupontMicrocircuit Materials (DMM), Research Triangle Park, N.C.) that mayalso be used as the electrolytic matrix. The advantage of using such amedium is its compatibility with screen printing technology and othermaterials from DMM to make a complete device. For example withconductive carbon black pastes such as 7152, conductive silver paste9145 and an encapsulation coating such as 7165 EL. All of thesematerials are compatible and processed using compatible technologies.Functionalized fluoropolyethers may be crosslinked using variouschemistries such by using co-monomers so that reactions with epoxy andisocyanates groups result in polymer formation. The co-monomers may benon-fluorinated. The monomers for solidification may polymerize byaddition or condensation polymerization. Those condensationpolymerizations are preferred which do not release any new smallmolecules, such as water and gases. Some of the preferred mechanisms arereactions between amines and epoxies, mercaptans and epoxies, amines andisocyanates, isocyanates and hydroxyl groups, Addition reactions may bering opening polymerizations or through the opening of unsaturated bondsand rings. To form a polymer which will solidify at low concentrations,those systems are preferred which form a three dimensional network. Thismeans that for condensation systems there should at least be one monomerwhich is trifunctional or of higher functionality. For polymers formingnetworks by addition polymerization, use of polyfunctional monomers(those monomers which have at least two polymerizable unsaturations) isrequired. As discussed below, for high speed printing methods highfunctionality monomers are desirable for rapid cure. Thus, other thanthe monomers, appropriate catalyst may also be required in theformulation. The details of materials, chemistry and reactions are wellknown and may be found in a standard polymer chemistry book (e.g., seePolymer Chemistry: An Introduction, by M. P. Stevens, Oxford UniversityPress, 1998). For low shrinkage it is preferred that those monomers beused which have high molecular weight (e.g., functionalized pre-polymersand oligomers), typically greater than 2,500, and preferably greaterthan 5,000. Since a preferred method to deposit the electrolyte is byprinting, and in printed processes the layers are thin from submicron toseveral tens of microns, and further these are fast processes, it isrequired that these are solidified fast and compatible with high speedweb processes as needed. One preferred way is by radiation such as UVpolymerization and the other by heat. For rapid solidification it isimportant that the gel point of the formulation is reached quickly, evenif further polymerization continues over time (e.g., shadow cure), oronly part of the monomer is converted to the crosslinked polymer in thefinal product. Depending on the curing system used, the curing rate ofthe coating may be reduced by ambient oxygen (e.g., free radicalpolymerization) or by atmospheric water (e.g., cationic polymerization).For this it is preferred that high functionality monomers be used sothat they will form the network even at low conversions. Thuspreferably, at least one of the monomers should have a functionality offive or greater. A source of high functionality acrylic monomers isSartomer (Exton, Pa.) such as dipentaerythritol pentaacrylate ester andpentaacrylate ester which have ten functionalities each (fivebifunctional groups).

Inert salts (e,g. lithium and sodium salts with preferably the sameanion as the ionic liquid if used) and acids may be used to promote ionconductivity. The cations from these can also be used to intercalateinto anodic and cathodic layers if used in devices. Viscosity modifiersare usually polymeric or fumed metal oxides, such as silica, titania andalumina. The fumed inorganic oxides in small percentage additions(typically less than 5% weight) can result in thixotropic formulations,so that the printed area is not prone to flow before it is solidified.These materials are available as hydrophobic and hydrophilic varieties,and either can be used depending on their compatibility with otherelectrolyte ingredients. Further, these are nano-sized particles andavailable in a variety of surface areas, and any of these can be usedwhich suit the processing and the properties. Some examples of fumedsilicas are Cab-O—Sil® M5 and H5 TS 720 and TS 500 from Cabot Corp(Billerica, Mass.). The first two are untreated fumed silicas, i.e. theyare hydrophilic and the last two are treated fumed silicas to imparthydrophobicity. Examples of other nanoparticles from Evonik (Parsippany,N.J.) are VP zirconium oxide 3-YSZ, VP zirconium Oxide pH, Aero Alu Cand Aeroxide® TiO₂ series such as NK960, T805, W2730X, W740X; and fromIshihara Corp USA (San Francisco, Calif.) TTO-55 series, TTO-51(A),TTO-51(C), and Titania Sol TSK-5. TSK-5 titania is coated with silicanano-particles (including fumed silicas, silsesquioxanes and titania) toprovide viscosity and/or UV shielding characteristics. Thenano-particles of titania may be doped with other metal oxides or becoated with amorphous titania or another oxide such as (aluminum oxide,silicon oxide and zirconium oxide) to reduce its catalytic activity whenexposed to UV radiation. Many of the products from Ishihara in TTO-55and TTO-51 series are coated with aluminum oxide or aluminum andzirconium oxide mixture. Opacifying additives with high refractive index(i.e., particles with refractive index greater than about 1.8 e.g.,silica coated titania, titania, barium sulfate, zirconia). Titaniumdioxide opacifiers may be purchased from Dupont (Wilmington, Del.), suchas Ti-Pure® R-101 R-102, R-103, R-104, R-105, R-450, R-706 and R-960.Preferred grades for use in the electrolytes are R-105, R-350, R-706 andR-960 as these are silica and or alumina coated (core shell structure)and reduce the interaction of titania with the electrolyte underillumination. To control permeability one may also use disc shapedsilicates which are generally clays that have thicknesses in thenanometer range. An example of these are montmorillonites and areavailable from Southern Clay Products (Gonzales, Tex.) (use of these aredescribed in U.S. patent application Ser. No. 12/468,719 (filed on May19, 2009) which is included herein by reference). Fillers may beselected to reduce cost or to impart other properties, such as thermalexpansion coefficient to match the other layers, enhancing specificmechanical properties, etc. Many of these are inorganic oxides, such assilica and silicates and also fibers (or nano-fibers) made of thesematerials. The fillers and opacifiers may be surface treated withcoupling agents to improve their compatibility with the electrolytematrices. Surfactants may be ionic or non-ionic. A variety ofsurfactants are available from 3M (Saint Paul, Minn.) under thetradename of Fluorads™ and Triton™ from Dow Chemical Company (Midland,Mich.). Adhesion promoters included coupling agents such as those basedon silicon, titanium and zirconium. Many of adhesion promoters are basedon silanes are available from Dow Chemical company, and those based onothers from Hubron Specialty Limited (Manchester, UK) under the tradename of Kenreact™. Many of the other additives, the tackifiers arematrix dependent and also dependent on the carrier solvent used todeposit the electrolyte layer. For example, Eastman (Kingsport, Tenn.)sells Tacolyn™ for aqueous systems, Foralyn™ for solvent systems, Foral™for radiation cured systems. For example an additive called Eco-Pure isavailable from Biotec Environmental LLC in Albuquerque, N. Mex. whichmay be useful for biodegradable polymers. This may also be used with abroader range of formulations with polymers such as substrates,electrolytes and other layers, conductors, binders and adhesives to makethem biodegradable. Many of these additives are synergistic with eachother and may fulfill multiple roles, i.e. surfactant may also help inreducing foam, filler may also be used to control viscosity and may alsoprovide a background color to the display, and a tackifier may be usedwithout coupling agents to promote good adhesion, etc. The purpose ofthis was only to show that the scope of the invention is not reduced byincorporating these additives. Biodegradability is an important issue,as many of the products made from this innovation (e.g., inexpensive anddisposable labels and tags) will end up in landfills in large numbers.Thus use of such materials and additives is important not just for thedisplay but for the entire tag and other components including otherelectronic components.

FIG. 3 a shows a schematic of an EC display device that is formed onpaper or fabric using printing processes or other processes. Printing orprintability in this disclosure means use of any printing or wet coatingdeposition method to deposit one or more layers in the device. Thisfigure shows a single pixel of the display that is formed by an EC layer32. The substrate (paper, fabric or a metal coated polymer or a metalcoated polymer film) is 34, the first conductive electrode 33, and thesecond conductive electrode 30, and an encapsulation layer 31 (one mayalso use conductive metal foil that acts both as a substrate and as aconductor. At least one of the two electrodes, i.e., 33 or 30 ispatterned. The two powering terminals are shown as 35 and 36. Thedisplay is viewed from the side of the arrow. EC formulations and layersusing hydrophobic materials are preferred although hydrophilic materialsmay also be used as described above. One has to be careful in applyingthe powering voltage to hydrophilic systems to ensure that unnecessarypower is not wasted by electrolyzing water rather than to activate thedisplay. For aqueous systems, it is preferred that the applied voltageis below 1.8V, and for hydrophobic system one may use up to 3V.

However, a preferred embodiment is where the entire device is made byprinting process. Here, one starts with a substrate 34, and all of thefollowing layers, i.e. the back conductor (33), the electrolyte (32),transparent electrode (30) and the encapsulant 31 are sequentiallyprinted on top of each other. Alternatively one may start with asubstrate 34 pre-printed with back conductor 33 and then print all ofthe other layers so that the complete device is printable and alignmentof one layer against the next is easy. This allows one to manufacturedevices at extremely low cost without mixing and matching otherprocesses such as lamination, edge sealing, etc. If this was a labelstock one can additionally print an adhesive layer (e.g., a pressuresensitive adhesive) and then combine this with a release layer. Theadhesive layer may also work as an encapsulation layer. As discussedlater when this is used, then during processing and after processingthere should be no adverse reaction between the layers (e.g., a nondesirable reaction, migration of a liquid or a molecular component fromone layer to the other, or solubilization of the underlying layer duringprocessing), but still have good adhesion. This issue of completeprintability, especially amongst these layers will be discussed later inmore detail. These devices are also connected to the other electroniccomponents (which are also preferably printed) by printed conductivelines.

Although this display may be processed by any method, the descriptionhere is particularly aimed to where all of the layers are deposited by aprinting technology. In addition, since different layers have differentcompositions, and may have different thickness requirements, it islikely that these are formulated differently, where more than oneprinting technique is used. Before coating the substrate with 33, it maybe optionally coated with a barrier layer (not shown) to preventingressof moisture and air or any of the chemicals from the paper or fabric topermeate into the device or any of the ingredients from the electrolyteto be transported away by wicking action. In addition, the barrier layermay also act as a planarization layer so that when other components suchas chips are assembled, then they form reliable contacts. The barrierlayers may be any of the polymers (including polymeric blends andalloys) that may be chosen from a wide variety of materials, e.g.,acrylates, fluorinated polymers, epoxies, polyurethanes, silicones,polyesters, alkyds, polyamides and biodegradable polymers such aspolylactic acid. It is generally preferred that hydrophobic or waterresistant materials be used. Materials with hydrophilic character mayalso be considered, particularly biodegradable polymers may be used toformulate barrier or other layers in the device (including electrolyte)so that disposal of these displays is not as serious an issue. Thethickness of this may be several microns and deposited by a printing ora coating process. Layer 33 may be a conductive paste or an ink that maybe patterned (e.g., printed) in a fashion to form electrodes (pixels)and the connectors. The thickness of this layer may be from about amicron to several 10 s microns. This may be a carbon comprising paste oran ink or this may be formed using the nanoparticles or coated nano orother particles as described in the concurrently filed non-provisionalapplication Ser. No. 12/497,535, entitled “Metal coatings, conductivenanoparticles and applications of the same”, attorney docket no.6232.109US, which application is incorporated by reference herein. Thetransparency of this layer is only needed if one needs to see throughthe device. The opaque conductive inks may comprise of two layers if oneof the layers may react with the electrode or the electrolyte. These twolayers may be formed using non-conductive polymers but filled withdifferent types of conductive particles. As an example, printableconductive silver pastes offer higher conductivity as compared to carbonpastes, but carbon pastes may be more inert. Thus one can place a carboncoating or a pattern that touches the sensitive electrolyte or theelectrode and then the silver on top, i.e. a conductive non-reactivelayer may be inserted between the high conductivity, reactive layer, andthe electrolyte or the EC electrode (both are being collectively calledEC layers). Other conductive non interacting pastes may comprise ofparticles of inert metals, conductive oxides and nitrides (like gold,rhodium, aluminum nitride, indium tin oxide, antimony-tin oxide,zinc-aluminum oxide, etc.). This can be used for any of the exampleswhere there is a fear of reaction between conductive electrode and theEC layers. One may even use an inert conductive electrode that wouldcover the electrolyte uniformly (applied as a tape or as a layer that ishardened). This material could be an anisotropic conductive adhesive(i.e. electrically conducts through the thickness and not laterally alsocalled “Z” conductive adhesive) or can be an isotropic conductor withlow conductivity (typically greater than about 500 ohms/square orpreferably greater than 2,000 ohms/square). The conductive pixels canthen be formed using printing on top of this carbon electrode usinghighly conductive adhesive or material. This material is typically lessthan 100 ohms/square, and preferably less than about 25 ohms/square. Adisplay formed using this concept is shown in FIG. 3 b that uponpowering displays two solid squares 36 b when one looks at these throughthe clear substrate 34 b. The transparent conductor is shown as 33 b andthe electrolyte as 32 b. The non-reactive low conductivity or thez-conductivity material is shown as 37 b. 38 b is an insulating materialand 39 b is the top conductor which is of high conductivity. Where thetop conductor touches layer 37 b, the device colors when powered byattaching a lead to the top conductor and another to layer 33 b. One canstart with a substrate coated with transparent conductor and thensequentially print the electrolyte layer, low conductivity layer,insulating layer and the top electrode layer. One could print a patternof insulating layer and the top conductor so that any desirable message,picture may be created that can be displayed as if there is one pixel orthere may be several pixels. Also, it is not shown in the figure, butone may extend the insulating layer so that it comes down on to thesides of the lower conductivity material and the electrolyte and coverspart of the transparent conductor 33 b. When the top electrode materialis put down the pattern is such that part of the electrode materialtouches 33 b (transparent conductor and then snakes on top of theinsulator without touching the pattern connected to that part which isforming the top electrode. This way both the bottom and the topelectrodes are in the same plane and it is easier to electricallyconnect to the rest of the system. One can screen print all of thelayers or for example some of these may be deposited using differentprinting methods. Typically the thickness of the electrolyte layer (32b) in such devices will vary from about 10 microns to about 300 microns.The thickness of low conductivity inert material will vary from about 1to 50 microns. The insulating layer 38 b is usually in the range ofabout 5 to 100 microns and the thickness of the conductive layer 39 bcan vary widely from about 0.1 to 50 microns.

The electrolyte layer should have good adhesion to the substrate andmust also present a surface on which other layers can be printed withgood adhesion. One way of forming this type of a layer is by using anelectrolyte which can be processed to a solid layer with a matrix withmicro or nano-pores that is filled with the electrolytic material (likechannels, also see FIG. 10 and description). The matrix provides goodadhesion to the underlying substrate (or electrode), supports theelectrolyte which may be liquid or soft solid, and also provides a topsurface that can adhere to the electrode that may be printed ordeposited on top (e.g., printable carbon black or metal filled polymers,or conductive polymers, such as PEDOT). To form this layer the printingformulation typically comprises of a solvent that solubilizes the matrixpolymer and also the electrolytic components (dissociable salts(including ionic liquids), redox dyes, non-removable solvents, otherpolymers that is compatible with the electrolytic components, etc).However, the matrix polymer is not compatible (does not solubilize) withthe electrolytic components. The electrolyte formulation may have otheringredients and fillers to control opacity, viscosity, adhesion, surfacetension, etc. When such a material is printed, and the solvent removed,the matrix polymer phase separates from the electrolytic components,resulting in a porous matrix filled with electrolytic components. Thevolume fraction of various components, layer thickness, processingconditions (e.g., solvent evaporation rate), matrix polymer propertiesand its molecular weight and other ingredients will determine thekinetics and thermodynamics of phase separation that will then determinethe microstructure of the pores. A preferred range of these channelssize (average diameter or cross-section dimension) that connect thebottom electrode to the top are preferably in a range of about 10 to5,000 nm. Such types of electrolytes may be used for other types ofelectrochemical devices which in addition to the displays includesensors, batteries and supercapacitors. Another method to provide thesame effect is to substitute a monomeric system instead of the matrixpolymer in the formulation, that is compatible with the electrolyticingredients (may also include a removable solvent for improvingprocessability), and upon polymerization (initiated by radiation orthermally) phase separates. The monomeric system may comprise of one ormore monomers along with reaction promoters and initiators.

The electrochromic layer (also electrolyte in this case) may comprise ofan electrochemically polymerizable monomer or a metal plating salt orboth as discussed earlier. Other materials including a complimentaryredox agent and other additives are also added. Polar materials, such aspolyvinylpyrrrolidone, may be used in the electrolyte. Hydrophobicmatrices with ion conductive properties are preferred, e.g., copolymersof fluorinated materials used in the lithium battery industry (e.g.,Solef® and Kynar® materials respectively from Solvay (Thorofare, N.J.)and Arkema (Philadelphia, Pa., some of the preferred Solef® grades are21216, 31508 and 11008) (see U.S. Pat. No. 7,300,166, which isincorporated herein by reference). Plasticizers are usually highdielectric liquids that are able to solubilize the dyes and monomers,such as propylene carbonate, polypropylene glycol, polyethylene glycol,esters, phosphates and ionic liquids. Several of the preferredplasticizers are those that would not migrate to the substrates or otherlayers, thus the preferred ones are ionic liquids, particularly the onesthat are hydrophobic. The ionic liquids may have anions such as ClO₄ ⁻,BF₄ ⁻, CF₃SO₃ ⁻, N(CF₃SO₂)₂ ⁻ (NTF or imide), CHF₂CF₂SO₃ ⁻,(CF₃CF₂SO₂)₂N⁻, (CF₃SO₂)₃ ⁻, As₆ ⁻, PF₆ ⁻, Cl⁻, Br⁻, trispentafluoroethyl-trifluoro phosphate (FAP or PF₃ (C₂H₅)₃). alkyl sulfate(e.g. C₂H₅SO₄ ⁻) and tetracyanoborate, The preferred anions are thosethat result in hydrophobic ionic liquids, which from the above list areNTF, (CF₃CF₂SO₂)₂N⁻, (CF₃SO₂)₃C⁻, FAP, alkyl sulfate andtetracyanoborate. The preferred cations are chosen from one of thefollowing: pyridinium, pyridazinium, pyrrolidinium, pyrimidinium,pyrazinium, imidazolium, pyrazolium, thiazolium, oxazolium, triazoliumand tetraalkylammonium. More details are found in the several patentsand applications that are already included herein by reference. Onepreferred hydrophobic ionic liquid is NTF salt of1-butyl-3-methyl-pyrrolidinium It is preferred that if an EC dye with asalt structure is used, one of its anion or cation be similar to theanion or the cation of the ionic liquid respectively. Opacifyingadditives hide the bottom electrode 33 so that it is not visible, andfurther when powered, a high contrast is obtained. Thickness ofelectrolyte layer may be from about 0.5 to 30 microns. The titaniacomprising particles provide a white color appearance due to thescattering of light between the particles and the media that they aredispersed in. However, one can also use inert pigments and dyes that maybe added to with or without the white pigments described above to changethe electrolyte/background color. When this is done we have to ensurethat when the electrochromic display is activated, the contrast is stillthere, and that this dye/pigment is inert, i.e., it does not adverselyaffect the EC phenomenon and is preferably UV stable and stable at theredox potentials used to activate the EC display. For example, for mostviologens that color to blue, blue-green, addition of yellow or redpigments (e.g., red iron oxide or a red organic dye) will still keep ahigh contrast. For molybdenum doped tungsten oxide EC material whichcolors to a neutral color, any color may be added to the background toblend it with the desired product aesthetics or design. Thus anycomplimentary color of the background to the coloration color of the ECmaterial would be acceptable. This allows one to fabricate printeddisplays in a variety of background colors by adding inert dyes andpigments. These pigments may also be used in formulations to hideelectrodes as discussed for the other devices below.

Layer 30 in FIG. 3 is a transparent conductor that is preferably formedby printing and comprises of conductive nanoparticles and/or largersized conductive fibers, as discussed in non-provisional U.S. patentapplication Ser. No. 12/468,719. As discussed earlier, this may have amatrix material, or may just be a non-woven transparent mesh. Afterdeposition (coating or printing process) this layer may be pressed intothe EC layer 32 to form a good contact. The thickness of this layer maybe about 0.2 to 20 microns. To show characters, images, etc, at leastone of the conductive electrodes is patterned (this is not shown in thefigure). Another way to pattern may be to pattern the electrolyte,particularly for passive matrix displays. The electrolyte may bepatterned as it is deposited, while filling the areas withoutelectrolyte with inert material but matched in color and thickness tothe electrolyte. One may also subject the electrolyte after printing toUV or other radiation beam which selectively crosslinks the matrix ordeactivates the EC dyes so that that area is not electrochromicallyactive. One may also employ photosensitizers or photoinitiators andadditional monomers to promote these reactions. As an example, a varietyof photosensitizers and photoinitiators are available from CibaSpecialty Chemicals (Tarrytown, N.Y.). It is also possible to makecomplete devices that are generic, and then expose them to UV throughmasks or writing by a beam to customize the message. As an example,rolls of generic devices may be made and stored, and when specificorders are received these are taken out of the inventory and the messagewritten and shipped.

Encapsulation layer 31 is a polymeric material that protects the ECmaterial and other components from water and air, and is transparent. Itmay be again chosen from several of materials, e.g., acrylates,fluorinated polymers, epoxies, polyurethanes, silicones, polyesters,alkyds, polyamides and biodegradable polymers. The biodegradablepolymers usually degrade to a substantial degree when these are put in alandfill or an industrial compostable facility. As an example, in onetype of system, lactic acid based polymers and copolymers are typicallyused for these purposes. Some of the main companies making these areBASF of Germany, Proctor & Gamble (Cincinnati, Ohio) Nature-works LLC(Minnetonka, Minn.), Novamont of Italy, and Rodenburg Biopolymers of theNetherlands. This layer may be a single layer or several layers withdifferent materials. For example this may be a three layered materialwith polyvinyl alcohol (a good oxygen barrier) in between twohydrophobic materials. This layer may also be printed, or even be formedseparately and then laminated to the substrate. Another method is todeposit this from a melt which can develop good adhesion with theunderlying layers. An example of a preferred encapsulation layer to beput on underlying urethane layers is made out of polyolefins where it ismodified to have good adhesion with urethanes (see Laura Weaver,Functionalized urethanes that deliver room temperature adhesion topolyurethanes”, presented at the Annual Technical Conference (ANTEC) ofthe Society of Plastics Engineers, Chicago meeting, 2009).

The contacts for the terminals for the display may be exposed so as toconnect to other circuitry.

An advantage of depositing most or all of the layers in a display byprinting is to integrate the display making process with otherelectronic elements that may be optionally printed, e.g., connectors, RFantennas, power sources (e.g., solar cells, capacitors) and integratedchips. For example PolylC (Furth, Germany) and Kovio Inc (Milpitas,Calif.) is able to print transistors and other circuitry, whereasNanosolar (San Jose, Calif.) and Konarka Technologies (Lowell, Mass.)have demonstrated printed solar cells. This can result in low costproducts such as tags or displays for a variety of applications inpackaging industry for inventory control, product authentication,anti-theft, tickets, gift cards, security control, product status, etc.as discussed in non-provisional application Ser. No. 12/468,719,published US Patent applications 20070114621A; 20080100455;20040022542A1 and Published PCT patent application WO08022972A1.

An alternate way of making the display is to deposit the conductiveelectrode on two different substrates and then use the electrolyte layeras the glue or the integration medium for these two with the conductivelayers facing the inside of the sandwich and touching the two conductivelayers.

FIG. 4 shows another example of an EC device that is formed on atransparent sheet 44 (e.g., a polymeric film). The two opposingelectrodes 43 and 40 are deposited by a printing process and are formedusing the TC materials described above. Instead of printing, one maystart out with a transparent conductor (such as indium tin oxide (ITO)or thin layer of gold) coated on a plastic sheet from many suppliers,which can be patterned by standard etch techniques. ITO, silver and goldmetal coated transparent substrates are available and one supplier is CPfilms (Martinsville, Va.) which has substrates available in aconductivity range of about 4.5 ohms/square to about 300 ohms/square. Ascompared to FIG. 3, the two opposing electrodes are in a side by side(interdigited) relationship, rather than stacked on top of each other.These figures are only to show the principles of layer configuration, asany of the devices described in this invention may be made in eitherconfiguration (interdigited or stacked layers), on substrates which aretransparent or opaque. For some applications it is preferred that thosesubstrates be used where one side has a mat (or textured) finish and theother side has a smooth finish. The display is built on the smooth sideand the display is viewed from the textured side so that specularreflections that give a glossy appearance can be avoided and some of thefaint visibility of the electrode patterning through the substrate canbe reduced. One may even adhesively bond a matt finished film on top ofthe surface through which the display is viewed to achieve similareffects. The electrolyte 42 comprises of the ingredients discussedabove. The device is encapsulated by layer 41 and powered via terminals45 and 46 (in all the figures these terminals are shown to be coming outof the substrate, but these may also be connected to a power source onthe substrate, such as a battery, antenna, a chip, solar cell, etc). Thedisplay is viewed from the side of the arrow. As an example when apolymerizable monomer that changes color upon polymerization (e.g.,bithiophene) and a complimentary redox couple (such as viologen) is usedand the terminal 46 is negative, the region in the electrolyte 42 thatis touching or close to the electrode 40 turns deep blue, whereas theelectrolyte area touching or close to the opposing electrode 43 willdeposit the polymer. The viologen will fade as it oxidizes by loosing aproton to the polymerized coating, and the colored area in the vicinityof the electrode 43 will stand out providing high contrast. This colorof polymerized material may change with time, if the oxidation of thepolymer changes which may occur by any one or more of the followingreasons; applying a reverse potential, shorting the two terminals,leakage of current through the electrolyte, or diffusion of oxygen intothe device. Alternatively (not shown in the figure) one could havedeposited a patterned inert and opaque layer (preferably similar incolor to layer 42 which may also be opaque) before depositing electrode40, so that any coloration in this area would not be visible. In factthe opaque layer should also cover any gaps between the pixels, so thatonly the desired pixelated areas are viewed. In this case the electrode(40) does not have to be transparent (this could be a black coloredpaste made out of conductive carbon particles and a binder). Another wayto make the display, is by lamination process (e.g., see U.S. patentapplication Ser. No. 12/140,054 for lamination procedures), where twosubstrates coated with conducting materials (one of which istransparent) are used. Typically on at least one of these the conductivepath is patterned. The EC material is deposited on one of them uniformlyor in a pattern and then the two substrates are laminated where ECmaterial is sandwiched between two conducting surfaces. When the deviceis powered, the EC material changes color to display information,depending on the electrode pattern. The EC layer may be deposited by aprinting process. In this application one of the substrates may also bea conductive metal foil and selective areas may be masked withnon-conductive layers as necessary.

FIG. 5 shows yet another variation where an opaque substrate 54 is used.The EC properties are in electrolyte 52 as described in FIG. 4. The twoopposing electrodes are formed as 50 and 53. Layer 51 is anencapsulation layer, and the arrow shows the direction of viewing.Essentially the electrolyte layer is deposited first and then theelectrodes are deposited (which was the opposite for FIG. 4). Ifterminal 56 is powered positive compared to terminal 55, the electrolyteregion close to the electrode 50 colors by polymerization and isvisible. Again as earlier, the electrode 53 can be masked and need notbe transparent. If one uses an electrolyte with a platable metal saltand a polymerization monomer, then the metal will plate on 53 in thearea touching the electrolyte and polymerization on 50 in the areatouching the electrolyte. One could mask one of these depending upon thedesired color, or even leave both unmasked in the color differentialbetween the two is desired.

FIG. 6 a shows another type of device in which an ion storage layer(this layer may also have electrochromic properties) is added to thedevice. The ion-storage layer is shown as 67 that is placed between thetransparent conductor 60 and the electrolyte is 62. The encapsulationlayer is 61 and the device is powered from terminals 65 and 66. Thesubstrate 64 is opaque and this viewed from the side as shown by thearrow. If the ion-storage layer is a cathodic type comprising oftungsten oxide, PEDOT, etc., then an anodic material polymerizationmaterial (e.g., bithiophene) is added to the electrolyte. Again theelectrode 63 may be masked and need not be transparent. When the deviceis powered with electrode 66 being negative, the ion storage layercolors by reduction if it is electrochromic. The ion-storage layer maybe formed in several ways as described in the concurrently filednon-provisional application Ser. No. 12/497,535 entitled “Metalcoatings, conductive nanoparticles and applications of the same”, whichapplication is incorporated by reference herein. A particularly novelway that is described in that application is to make a printableformulation of EC materials that combines an EC material (or an ionstorage material) in a matrix with electronically conductivenanoparticles. EC materials, such as inorganic oxides (e.g., tungstenoxide), may be coated on particles that are conductive or non conductiveand then incorporated in the EC layer formulation. Another way is tomake these as nanoparticles (these oxides should have at least onedimension smaller than 500 nm, preferably less than 100 nm) and thenincorporate them in the formulation. The matrix composition for thiselectrode layer, other than the presence of electronically conductiveparticles and the EC dye may be similar to the electrolyte. If the coloris desired from the electro-polymerization product at the otherelectrode, the ion-storage electrode may be masked and the other onemade visible. Another combination of materials that may be used to forman EC device is combining an ion-storage material that oxidizes bytaking in anions, or by releasing the cations, and the electrolytecomprising of a metal platable salt. As a specific example, the EC layermay be reduced polyaniline (e.g. see U.S. Pat. No. 6,327,069 which isdeposited by mixing an electrochemically inert reducing additive to aelectrochemically active material, where the latter is polyaniline),nickel oxide, iridium oxide, cobalt oxide, etc, to name a few. When thedevice is activated, the metal plates on the negative electrode, and theabove layer is oxidized. Another type of ion-storage electrode that maybe used is capacitive. For example, U.S. Pat. No. 6,118,573 (which isincluded herein by reference) describes such electrodes. These generallycomprise of activated carbon and graphites. Powders of these materialsare mixed in a matrix (e.g., polymeric or a solvent) and then deposited.These electrodes may also serve as conductive electrodes. To enhancetheir conductivity, one may add carbon nano-tubes to these.

The encapsulation layer in EC devices, e.g. such as component 31, 41, 51and 61 in FIGS. 3, 4, 5, 6 a and 6 b respectively or in otherembodiments may also be an adhesive tape with a pressure sensitiveadhesive or one that will cure later with radiation or heat or withmoisture or by expelling oxygen (anaerobic). The backing in these tapesmay be a polymeric film (e.g., polyester, polyimide, polystyrene andpolyolefins), cloth, metal (e.g., aluminum, copper, steel) or metalizedpolymer foils (e.g., used routinely in food and other packagingindustry). The adhesive tape may or may not have good adhesion to thelayer underneath, but there may be other layers or substrate that may beexposed around the perimeter of the non-adhering layer to which the tapeis bonded to.

For those reversible displays and indicators, when power is removed onewould like to control the persistence of the indicator or the display,one may also make use of selective ion conduction layers (SITL) whichmay be inserted between the ion storage layer and the electrolyte (SITLis shown in FIG. 6 b as layer 69). These are described in U.S. Pat. No.6,178,034. SITL layer retards the ionic flow and may only allow one typeof ion (e.g., cation vs anion) to go through. As a specific example, theelectrolyte may comprise of platable metal salt and the ion-storagelayer may be reduced polyaniline as described above. SITL layer in thiscase will be a chloride anion conductor (e.g., an anionic polymer, e.g.,see PCT patent application WO2007/084155). These layers are usually putdown as thin coatings from solutions in a thickness preferably less than2 microns thick. When the device colors by metal plating the anion isretained by the ion-storage layer. Depending on the permeability of thislayer, once power is removed, the ions can percolate through this layerinto the electrolyte and recombine with the metal to erase theinformation. Using SITL layers (type and thickness) can change thememory (or image retention) of a device from several seconds to severaldays and longer.

FIG. 7 shows a device where the contrast is produced by a platablemetal. Substrate 74 is coated with a conductive material 73 and thenwith an electrolyte 72. The top TC is patterned as shown by 70 and thenencapsulated by 71. For a device that needs to be only viewed from thetop side, one or both of 73 and 72 are opaque. For example 73 may be acarbon electrode and 72 is transparent. When power is applied with thetop electrode being negative, metal deposits at the interface of 70 and72 and gives a reflective contrast against carbon black. The electrolytemay have white opacifiers resulting in contrast against a whitebackground. The electrolyte may comprise of 1-methyl-3-octyl imidazoliumchloride as ionic liquid and silver chloride as basic electrolyte withother ingredients added as discussed earlier. One may also add acompatible anodic redox material to the electrolyte, or the electrode 73may comprise of activated carbon which would result in capacitiveion-storage layer. An alternative method of patterning the conductivelayer in this example or any other example (not shown) is by using acombination of a conducting and an insulating layer. This isparticularly useful where the processes do not allow an easy or aninexpensive way to pattern by selective removal of the conductivecoating. As an example an insulating material in a pattern may bedeposited on layer 72, which may be patterned in a desired way, so thatwhen the conducting layer 70 is deposited uniformly so that it onlycomes in contact with layer 72 where the insulating layer is absent.

FIG. 8 shows another type of device which functions on removing oroxidizing a metal to create a contrast. Substrate 84 is coated with aconductor 83, which is further coated with a metal 87 which would beselectively removed or oxidized when the device is powered to create thecontrast. The thickness of the removable metal is usually in the rangeof 10-40 nm. 82 is the electrolyte, 80 is patterned TC and 81 is theencapsulation layer. As an example if layer 87 is vanadium, one may usevanadyl sulfate as the redox species in electrolyte 82. When the deviceis activated with 80 being held at a negative potential, the areas below80 are oxidized to a colorless state and result in a contrast with thesurrounding area. In this case electrolyte 82 is clear. Anotheralternative may be that 87 is a silver layer, and the electrolyte asilver ion conductor, which could comprise of powders of inorganicsilver ion conductor (e.g., silver β alumina, RbAg₄I₅, Ag₁₉I₁₅P₂O₇)along with 1-methyl3octyl imidazolium chloride as ionic liquid andsilver chloride as basic electrolyte. The electrolyte may haveadditional opacifiers if the opacity provided by the above powders isnot enough. When a negative voltage is applied to 80 relative to 83,silver from layer 87 is stripped off and deposited at the interface of82 and 80 resulting in high contrast. In this case it is not necessaryto remove the silver through the entire thickness of layer 87, and it ispossible that if this layer is thick enough it can work both asconducting layer and as metal provider, thus layer 83 is not needed. Inthis device any appropriate thickness of silver layer may be used.

Although some of the above examples are provided using interdigitedarrangement (for example FIGS. 4, 5, 6 a and 6 b) and some parallelarrangement (FIGS. 3, 7 and 8), it should be noted that any of thesedevices may be made in any of these arrangements. If the electrodes areon two different substrates, then one may form these devices bylamination, where either the electrolyte or one of the other layers maybe used as a medium to bind the two substrates. Interdigited electrodesmay also be formed for display system, which allows all electrodes to belocated in the same plane as discussed in FIGS. 4, 5, 6 a and 6 b. FIG.9 shows a method to form characters using two connections with both theelectrodes on the same substrate. In this case, the characters areformed by a close separation of the two electrodes 91 and 92, and then alarge separation of the two electrodes creates boundaries that do notcolor such as in several areas (only one of these is indicated by 90).The closeness of separation that allows one to color is dependent on theelectrolyte conductivity, but it is generally preferred that this beless than about 1 cm. A most preferred range is that which can beaccommodated in the label or tag and conveniently formed by a processingtechnique used. If a laser etch is used to make these lines then aconvenient range is 10 to 100 μm, and if printing is used so that thetransparent conductor is not printed in those areas, then it may be morein the range of about 0.1 to 1 mm. Another way to use high conductivityelectrolytes (to allow faster coloration) but also allow closercharacter spacing is to use patterning of the electrolyte so that theelectrolyte while touching both the electrodes, is separated for eachcharacter. Since the electrolyte may be easily visible (e.g., milkywhite appearance), one may use color matched insulating separator paintsor layers. As an example, one may print these separators on thesubstrates first (say in regions 90, or even extending them vertically(or making them in other shapes) and then print the electrolyte. Theelectrolyte pattern may overlap the insulating layer edges, butpreferably not touch each other if the characters are too close. If theytouch, their appearance in the covered areas can still be masked by theinsulator, but unnecessary power will be consumed. In this example onlytwo electrodes are used to form the characters, but may form severalleads coming in to power each segment of the character differentiallyfrom the controller, so that any message at will can be displayed byselectively powering these segments.

Printing processes may be used to deposit any one of the layers in thedevice including electrodes, electrolytes, masking, barrier andencapsulation layers. Printing processes include individual or web basedprocesses such as offset lithography, engraving, thermography,reprographics, letterpress, screen printing, flexography, gravure, padprinting, ink-jet printing and laser printing. Printing methods allowone to pattern the electrodes, electrolytes and other layersinexpensively, particularly for display and indicator applications thathave to be prepared in large numbers at an attractive cost.

Transparent conductors are required to form these devices, and apreferred option is to deposit these layers by printing. Many of thedevices are being developed so that the various layers comprising thesecould be deposited by a solution coating or a printing method.Conventional TC's, such as indium tin oxide, fluorine doped tin oxide,and aluminum doped zinc oxide are usually deposited by physical vapordeposition. To make the devices of this invention one may use such TCs.As an example, one may obtain polymeric films with predeposited TC'swhich may then be patterned by removing or etching the TC. For sometypes of devices and applications it is economically desirable that alllayers including TCs be deposited using printing processes. For mostapplications the transmission of the printed TCs should be as high aspossible. For solution deposited or printed TCs, transparency should bein the wavelength range of 400 to 700 nm. Many times, the transparencyof these conductors is characterized in photopic range or at 550 nmwhich is for maximum eye sensitivity in the daytime. For applicationsinvolving colors, transparency in a broad range of 400 to 700 nm ispreferred. A transmission in excess of 30% is acceptable for someapplications. A transmission in excess of 80% at the desired wavelengthon a substrate is most desirable. In terms of surface resistivity thesevalues should be less than about 10,000 ohms/square, and more preferablylower than about 200 ohms/square, and most preferably lower than about100 ohms/square. Thus a substrate with most preferred transparentconductor deposited by solution or a printing process will have atransparency greater than 80% and a surface resistivity lower than 100ohms/square. If a colored or a hazy substrate is used, that willnaturally lower the transmission, however, to evaluate the relativemerit of a transparent conductor, the substrate should be clear.

Printable TCs using randomly dispersed conductive nanowires (made out ofmetals, such as silver, silver alloys, noble metals, and semiconductorssuch as indium tin oxide doped zinc oxide and carbon nanotubes) havebeen suggested for use as transparent conductors and electricalconnectors (for example see published US patent application 2007/0074316by Alden et al and the concurrently filed non-provisional applicationSer. No. 12/497535 entitled “Metal coatings, conductive nanoparticlesand applications of the same”, which application is incorporated byreference herein. Specifically, conductive nanowires made out of ITO arediscussed by Limmer, S. J., et al., (Applied Physics A: MaterialsScience and Processing 79 (3), pp. 421-424 (2004)) and for carbonnanotubes by Trottier, C. M. et al., (Journal of the Society forInformation Display 13 (9), pp. 759-763 (2005)). The contents of thesepatent applications and articles are included herein by reference. A lowtemperature processable, screen printable conductive transparent layerwith non-silver is available from Creative Materials Inc. (Tyngsboro,Mass.) as 124-31, which may also be used. Since an important focus ofthis invention is printability of the materials, it must be understoodthat other than the nanowires, additives including a matrix materialwill be required to form a complete ink formulation for printing TCsdepending on the print process used. This includes agents to controlviscosity (including thixotropy), surface tension, drying control,antifoaming agents and others. Any printing methods may be used that aresuitable for the product and conforms to the layer thicknessrequirements. For those layers where high deposition uniformity isrequired in a pattern with thicknesses generally lower than 2 microns,one of the preferred methods of print deposition is by MasklessMesoscale Materials Deposition by Optomec (Albuquerque, N. Mex.). Thisprinting/spray method may be used to deposit conducting and or otherlayers in the device. Corrosion inhibitors are added to these silvernano-fiber materials, which may be the same as the UV stabilizersdiscussed above. Further, one may use the same UV stabilizer to reducecorrosion of the silver nanowires as the one used in the electrolyte.Some examples of corrosion inhibitors are aromatic triazoles, imidazolesand thiazoles, cysteine, and synthetic peptides and protein scaffoldswith affinity towards the metals, dithiothiadiazole, alkyldithiothiadiazoles and alkylthiols, anti-tarnish varnishes. Coating withgold, and alloying with other elements have also been suggested toreduce corrosion (a more exhaustive description of alloying elements andcoatings to reduce corrosion are described the concurrently filednon-provisional application Ser. No. 12/497535 entitled “Metal coatings,conductive nanoparticles and applications of the same”, whichapplication is incorporated by reference herein. Further one may alsouse metal coated organic fibers to form transparent conductors asdescribed in this invention. In some cases conductive polymers may alsobe used which can be easily deposited by printing. One may takeadvantage of the redox properties of these polymers and save on adding aredox dye to the electrolyte, but one has to ensure that the redoxproperties do not adversely affect the device performance when thedevice is activated. Conductive thiophene solutions (e.g., Baytron P)are available from HC Starck (Newton, Mass.) and as Orgacon from AgfaGevaert (Belgium, or from ITO America Corporation, Tempe, Ariz.), andconductive polyaniline solutions (e.g., Panipol T, M, X, W and L) fromPanipol Oy (Finland). Agfa-Gevaert also supplies polymeric films coatedwith thiophenes. It is preferred that the printable TC be deposited ontop of the electrolyte so that the conductors form a good contact (theymay even be pressed into the electrolyte surface) and then these couldbe covered with a layer of inert polymer for encapsulation of thedevice. Several inert polymers are described in this invention, some ofthem are acrylates, fluorinated polymers, epoxies, polyurethanes,silicones, polyesters, alkyds, polyamides, polyxylene (e.g., Paralyene™C, D or N polymers) and biodegradable polymers such as polylactic acid,etc. These polymers may also be polymerized (and/or crosslinked) in situafter they are deposited.

Usually the nano-wire dispersions are prepared in aqueous systems. Ifhydrophobic electrolytes are used, then such dispersions will bedifficult to print on top of these electrolytes. One may use surfactantsor partially or fully replace the solvents to those that may be morecompatible with the underlying layers and also tailor their surfacetension and viscosity in a range that is acceptable by the choice ofprinting method. Patterning of the printable TCs may be done by printingmasks or printing selectively (e.g., by inkjet printing)

The devices may also be made in another way, wherein the electrolyte isincorporated in a porous medium, which is then assembled so that theelectrodes touch different areas of the porous medium. The porous mediummay be continuously impregnated by an electrolyte by a printing processand then laminated between two electrodes. The porous medium may havecylindrical channels perpendicular to the electrodes so that theelectrolyte does not permeate sideways, or these may have interconnectedpores where the electrolyte migrates all over the place. Further, thesemembranes are typically prepared in advance of impregnating them withthe electrolyte. In another embodiment, the electrolyte is mixed with amonomer and assembled in the device. The monomer is later cured whichthen results in phase separation of the electrolyte from the polymer ina way that the polymer forms reticulated structures, or polymericchannels with liquid electrolyte are formed due to this phaseseparation. Some examples of porous media are papers, glass fiber orpolymeric fiber filters, open cell foams, polymeric membranes withperforations, etc. Some specific examples of filters are Whatman 541,mixed cellulose ester membranes, nylon and PTFE membranes (availablefrom Fisher Scientific, Pittsburgh, Pa.). Preferred membranes have apore size of less than about 30 μm and preferably less than about 10 μm.Some membranes that have non-interconnected holes perpendicular to thesurface of these membranes are Millipore Isopore® polycarbonate(Millipore, Billerica, Mass.) and Whatman Anopore aluminium oxidemembranes (Whatman Inc, Florham Park, N.J.). Phase separation ofpolymers with liquid crystal systems is well known (polymer dispersedliquid crystals (PDLC), such as polymerization induced phase separationin U.S. Pat. Nos. 6,061,107; 5,691,795). Usually acrylics, epoxies andurethanes are utilized for these purposes. In PDLC systems the liquidcrystals are encapsulated in a droplet, whereas here open channels areneeded so that the liquid electrolyte is able to touch the electrodes.FIG. 10 shows an schematic diagram of such a system where two substratesare shown as 10 a and 10 b that have conductive coatings 10 c and 10 drespectively. The electrolyte is shown to have two components, a solidphase that forms the channels, shown as 16 f, and the channels filledwith the electrolyte as 10 e. Although these channels are not shown tobe interconnected, they may also be interconnected as discussed earlier.

A novel electrolyte formulation may be formed in another way thatutilizes a porous structure. These may be formed using environmentalfriendly methods using water as solvent. As an example, an anodicallypolymerizable monomer (e.g., thiophene) as described earlier and acathodic material may be solubilized in a water soluble ionic liquid. Anexample of water soluble ionic liquid is 1-Ethyl-3-methylimidazoliumethylsulfate available as LQ1 from BASF (Florham Park, N.J.). If aviologen based cathodic dye is used, it is preferred that its anion bealso ethyl sulfate. Since this ionic liquid is water soluble, this canbe mixed with polymeric based water based latex or a colloidalformulation (e.g., latex, acrylic (including polyvinyl chloride,acetates, butadienes and isoprenes), urethane, epoxy, silicone andfluoropolymer latex or emulsions) which may optionally include otheradditives as described earlier. This may also be made in a aqueous pastewhich is screenable for printing. The print is then dried by typicallyheating from 80 to 110° C. for a few minutes. The drying process leadsto the emulsion or the latex particles to coalesce and/or crosslink toform a water resistant coating with good adhesion to a variety ofsubstrates, while leaving interconnected pores filled with electrolytecomprising predominantly of the ionic liquid with redox materials.However, it is important that the drying or processing conditions bechosen (including the eventual conditions that the device is subjectedto) so that the particles do not flow completely and result innon-porous film formation. Some ways to avoid this are to includeparticles which have a glass transition temperature higher thanprocessing or use conditions, or use particles that are alreadycrosslinked. For those devices where one of the redox is in one or morecoatings, the electrolyte may be modified with appropriate redoxmaterials, salts or compositions. This allows one to form anenvironmentally friendly, printable electrolyte composition which usesno solvents other than water.

Preferred materials to form a solid matrix (or sometimes called abinder) of various layers using multi-phase materials, particularlypolyurethanes is discussed. Polyurethanes in this disclosure includepolyurea linkages where instead of a polyol linking with isocyanate alinkage between an amine and an isocyanate is formed. A polymer may haveboth urethane and urea linkages. This aspect is described with referenceto FIG. 3 c, but the principles are applicable to other devices as well.The arrow in this figure is the direction of viewing of the display. 34c is a transparent substrate, 33 c is a transparent conductor, 32 c isan electrolyte layer with redox dyes, layer 30 c is the back electrodeand layer 31 c is the encapsulation layer where all of these aredeposited by printing followed by a drying or a curing step in between.Additional insulating layers other than encapsulants when used refer tothose layers that are not electronically or ionically conductive.Polyurethanes are chosen so that we can use its multi-phasemicrostructure to a great advantage. In addition it offers a veryversatile platform to change its chemical, morphological and physicalproperties. Polyurethanes form hard and soft domains, where hard domainsare inter-dispersed within a matrix of soft domains on a nanometer scale(e.g. see, Eisenbach, C. D., Ribbe, A., Gunter, C., Macromolecular RapidCommunications, 15 (1994) p 395-403). The hard domains may becrystalline or form an amorphous area with high glass transitiontemperature. Similarly, other polymers with multiphase structures (e.g.,with crystalline and amorphous phases) may also be used. In thesematerials the electrolytic or the EC components are restricted to thesoft domains while the hard domains provide good adhesion and mechanicalproperties. We prefer to use aliphatic urethanes to ensure good inherentelectrochemical and UV stability. Thermoplastic urethanes areabbreviated as TPU. The size and density of the domains can be tailoredby altering the monomer ratio. The size and density of the domainscontrols the mechanical properties, electrolyte uptake (when used forthe electrolyte layer) and adhesion.

TPUs of different properties are typically synthesized using varyingstoichiometries from three bifunctional monomers and a catalyst. Themonomers are a diisocyanate (TSO), a low molecular weight chain extenderdiol (CE) and a higher molecular weight flexible diol (FD). The ISOreacts with a hydroxyl group of the CE or FD. The sequences that formfrom the reaction of ISO and CE are called rigid segments and thesequences formed from ISO and FD are called the flexible segments.Sequences are also formed that are mixtures of ISO, CE, and FD.Sometimes ISO is reacted with CE so that an isocyanate terminatedprepolymer is formed, which is then reacted with FD. This provides moretailored rigid segments that form hard domains. Once the urethane issynthesized, the rigid segments separate into hard domains that actsimilar to crosslinks and the soft segments provide the flexibility.This provides rubber like elasticity to these materials which can bereversibly stretched. Typically the soft segments form a continuousmatrix in which the hard segments are embedded as discrete entities thatseparate on tens of nanometer scale.

One can synthesize a TPU so that the electrolytic components (e.g. theionic liquid and the dye in this case) are contained in the softsegments, i.e., the electrolytic components can swell the TPU but cannotsolubilize it. Additional processing solvent is required to solubilizethe TPU so as to solvate the hard domains. This allows one to form apaste or a solution for processing, such as for screen printing or forany other method. After printing this layer, the solvent evaporates (oris extracted), and the hard domains are formed by phase separation thatresults in the solidification while the soft segments retain theelectrolytic components, which form continuous pathways within theelectrolyte layer for ionic conduction. The compatibility of the softsegments can be tested before hand by seeing if the FD monomer dissolvesin the electrolytic liquid (or even the dominant liquid phase which maybe just the ionic liquid or any other liquid medium used for theelectrolyte). A polymer between ISO and CE may be also formed and testedfor its inertness towards the electrolytic components and its solubilityin a desired solvent.

For an electrolyte formed from an ionic liquid(1-butyl-3-methyl-pyrrolidium bis(trifluoromethylsulfonyl)imide, alsocalled BMP-NTF), we found that TPU (called TPU1) formed usinghexamethylene diisocyanate as ISO, butanediol as CE and a polyesterpolyol as FD, could be swelled and gained 40% weight when immersed inthis ionic liquid. This swollen mixture dissolved when dimethylsulfoxide(DMSO) as processing solvent was added. Another hydrophobic urethane wasselected called TPU2 with a polyether FD. TPU2 had a very differentinteraction with the electrolyte even though TPU2 contained the sameisocyanate and chain extender as TPU1. This is because TPU2 used ahydrophobic polyether for flexible segments (FD); where as TPU1 used apolyester. Both TPU1 and TPU2 have similar mechanical properties (100%tensile modulus for TPU2 was 250 psi vs 300 psi for TPU1). When TPU2 wassoaked in BMP-NTF ionic liquid, no change in weight was seen, i.e. therewas no swelling, indicating that there was no interaction between theBMP-NTF and the TPU2, thus our electrolyte would not migrate into any ofthe layers made of TPU2. TPU2 was also not soluble in DMSO. Further,when a pellet of TPU1 and TPU2 were pressed together under heat, theydeveloped excellent adhesion and the overlapping regions could only bepulled apart by tearing one of the polymers. This shows that the twopolymers bonded well due to similarity of the hard segments. Thus alayer made out of TPU can be processed using another solvent, and willnot dissolve the underlying electrolyte layer, will not soak theelectrolytic components and will develop good adhesion. TPU2 can be usedto develop a matrix for conductive formulation for layer 30 c in FIG. 3c that can be deposited on top of the electrolyte layer 32C formed byTPU1. If the mechanical properties of both the layers are matched in thetemperature range of interest, then upon flexing a device with theselayers the interfacial stress would be low, thus avoiding failures.Similarly for the encapsulation layer for this system, one can pick athird urethane say TPU3 which has similar ISO, CE, but a differenthydrophobic ED based on another polyether that is not compatible withthe ionic liquid (meaning does not absorb) and also different from theone used in TPU2. This can then be used as an encapsulant layer 31 c inFIG. 3 c, and yet a third solvent could be used. Thus, printable deviceswith high durability can be obtained where these use hydrophobicmoisture resistant matrices. Again it is preferred to use a TPU3 whichhas similar mechanical properties when compared to TPU1 or TPU2.Mechanical properties similarity mainly refers to a modulus value of thepolymers which needs to be within a factor of 2 of the different layersin the temperature of interest and particularly at room temperature (25°C.). One may also measure the mechanical properties of the finishedmaterial with fillers and similarly match their mechanical properties.The mechanical properties of the thick layers (for those layers wherethe thickness is greater than about 1 micron and preferably greater thanabout 10 microns) can be tailored in another way to have low interfacialstress. They are chosen so that they can have high plastic flow understress to mitigate bending stresses or their elongation is high withoutfailure compared to the deformation stresses introduced on bending.

Polymer blends with multiple polymers may also be used for theelectrolyte layer. One of these polymers may be biodegradable to alloweasier degradation of the electrolyte when disposed. The materials thatare chosen should have at least one phase (if they are multiphasepolymers) that is soluble or compatible with the liquid phase of theelectrolyte, which could be the ionic liquid. Further, from a processingperspective, it is preferable that all polymers used are solubilized inthe processing solvent or in the mixture of the processing solvent andthe liquid phase of the electrolyte. As an example, some of the polymersthat can be used with the BMP-NTF liquid phase and are compatible withit are the polyurethanes described above, polyvinylpyrrolidone andpolypropylene carbonate. It is preferred that the polymers used are notelectroactive (i.e., they are inert) and that the liquid phase of theelectrolyte comprise of electroactive materials, if used. In the USpatent application 20090078917, the electrolyte comprise of twopolymers, one of which is electrochromic (or electroactive, i.e.,undergo redox reaction when the device is activated). Since theelectrochromic properties of electrochromic materials in the electrolytecomes from their mobility, using an electrochromic polymer places severerestrictions on their mobility and hence device kinetics. Such devicesare not useful for displays that need to be powered quickly in less than30 s, and more preferably in less then 10 s and most preferably in lessthan 2 s. The disclosure in this referenced patent application alsocomprises of polymers that are hydrophilic and meant for lamination withrigid substrates, however, their use in printed or flexible devicesleads to poor device storage characteristics.

The encapsulation layer does not have to be opaque, this can also be aradiation or thermally cured polyurethane. In case this choice isexercised it is preferred that the ISO and the CE be similar to theunderlying TPU2. Thermally crosslinkable polyurethanes have acrosslinker present in the formulation (isocyanate or polyol) with afunctionality greater than 2. For those that are crosslinked byradiation, low molecular weight urethane prepolymers are formed whichare terminated by acrylates or methacrylates and mixed with various UVsensitizers and absorbers. When subjected to radiation, the acrylicgroups form links by addition polymerization.

In the description of the device in FIG. 3, it was mentioned that theelectrolyte layer could be patterned so that the image looks sharp andthat the rest of the area is filled in by a color matched inertmaterial. This inert material can be formulated from TPU2, so that theelectrolytic components do not migrate from the patterned electrolytelayer to the adjacent inert layer.

Thus, by engineering the correct TPU chemistry it is possible to developmatrices for various layers, e.g., electrolyte, conductive layers (madeby filling the polymer with conductive particles), and insulating layersusing various TPU chemistries. These materials can be processed fromdifferent solvents so that there is no interaction during processing andelectrolytic components can be prevented from migrating between layers,have good adhesion between the layers, and have similar mechanicalproperties so that in bending extra interlayer stress is not introduced.The modulus and the soaking capacity of the TPU (where FD is compatiblewith the electrolytic components) can be tailored for a given ISO, CEand FD by changing the proportion of CE to FD (as both are polyols)while still maintaining a stoichiometric balance with the ISO, and alsoby changing the molecular weight of the FD while keeping the samechemistry. A preferred ratio for CE:FD for urethanes to be used inprinted and/or flexible displays is generally between 1:1 to 1:3, and apreferred molecular weight of the FD is between 600 to 10,000.

A non exhaustive list of aliphatic isocyanates is 1,6-hexamethylenediisocyanate (HDI),1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane (isophoronediisocyanate, IPDI), and 4,4′-diisocyanato dicyclohexylmethane (H12MDI)cyclohexane diisocyanate (CHDI), tetramethylxylene diisocyanate (TMXDI),and 1,3-bis(isocyanatomethyl)cyclohexane (H6XDI). As many of theseisocyanates are toxic when inhaled, these are converted to largermolecules, such as biurets, dimers, and trimers, etc., and then used tomake the urethanes. Although aromatic isocyanates are not preferred dueto their poor UV and electrochemical stability, they may be used in somelayers (such as insulators and encapsulants) with appropriate UVadditives. Some aromatic isocyanates are toluene diisocyanate (TDI),diphenylmethane diisocyanate (MDI, p-phenylene diisocyante (PPDI),naphthalene diisocyanate (NDI), and o-tolidine diisocyanate (TODI). Someof the popular hydrophobic polyols for FD that are based on ethers arepropylene oxide polyol, polybutyleneoxide polyol, andpoly(tetramethylene ether) polyol. Ester based polyols for this purposeare too numerous to list as these are made by reacting a number ofdiacids and diols. Some of these diacids are adipic, glutaric, pentaoicand azeloic acids and some of the diols are ethylene glycol, diethyleneglycol, propylene glycol, tetramethylene glycol and neopentyl glycol.Polycaprolactone diols are also popular for good hydrolytic stability.Some of the other polyols for FD are polycarbonate polyols andpolybutadiene polyols. Some of the chain extenders are ethylene glycol,propylene glycol, triethylene glycol, tetraethylene glycol, propyleneglycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol,1,3-butanediol, 1,4-butanediol, neopentyl glycol,1,6-hexanediolethanolamine, diethanolamine, methyldiethanolamine andphenyldiethanolamine. Some of the higher functionality polyols (greaterthan 2 from crosslinking) are glycerol, trimethylolpropane,1,2,6-hexanetriol, triethanolamine, pentaerythritol, N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine, diethyltoluenediamine,dimethylthiotoluenediamine. Some of these polyols may also be replacedby polyols from renewable sources such as soyabeans and castor oils.These polyols are available in a wide variety of functionalities andcharacteristics. Dow Chemical Company (Midland, Mich.) amongst manyothers produces polyols from renewable sources. Although in most casespreformed urethanes with the above components are used for the variouslayers, if these are to be formed, then some of the preferred catalystsare organometallic compounds based on, tin (dibutyltin dilaurate),bismuth (bismuth octanoate), and zinc. It is always preferred to usecatalysts in the lowest concentrations particularly for TPU1 as thesemay show electrochemical interference. A preferred range is about orbelow 1% of the polymer and more preferably below 0.1%. For moreinformation on reactivity, concentrations and sources of materials andprepolymers reference standard books (e.g., Szycher's Handbook ofPolyurethanes by M. Szycher, CRC Press, NY, 1999) or literature from thematerials manufacturers can be used.

Conductive paste can be made by adding conductive carbon black (usuallyabout 15-25%), dispersant or surfactant (<0.1%)), and a thixotrope suchas fumed silica (˜2%) to the polymer. These are mixed along with asolvent in a high shear mixer at our laboratory to get a uniform paste.One may also add conductive carbon nanotubes along with the conductivecarbon black or just use the nanotubes. As an example, Cabot Corporationin Billerica, Mass. is a supplier of conductive carbon blacks, andNanocyl in Belgium is a supplier of single and multiwalled carbonnanotubes. The carbon blacks and the carbon nanotubes may be surfacetreated to increase compatibility with the urethane. These companiesoffer several choices of surface treatments, some of which are aminesand carboxyl groups. Typical concentrations of carbon nanotubes are 1-3%and of carbon particulates about 20% to get the conductivity propertiesin a range of 80 to 150 ohms/square in a thickness of about 25 μm.

Some of the preferred solvents for forming processable pastes andsolutions are diethylene glycol monoethyl ether acetate, diacetonealcohol, dimethyl sulfoxide, 2-butoxyethyl acetate,1-chloro-4-trifluoromethylbenzene, ethyl lactate) and d-limonene,dibasic ester (includes all compositions available from Invista Inc,Wilmington, Del.), tripropylene glycol methyl ether, butyl acetate andpropyl acetate or their mixtures.

For completely printable EC devices there are several variations thatcan be adopted as has been discussed in various device constructions.Some of the interesting ones are described below. Many of these use oneEC layer that also serves as the electrolyte. Some of the EC layers arenot electrochemical, but their chromogenic properties are activated bythe application of electric field. For electrochemical electrochromicdevices, the electrochromic layer may comprise of additional layers,e.g., an electrolyte layer which is mainly used for ion conduction andone or two redox layers (i.e., those layers that undergo oxidation andreduction and may also be electrochromic). If these layers are used inaddition to the electrolyte layer these are simply inserted asadditional layers by introducing additional processing steps beforedepositing the electrolyte layer and after it is deposited. Any of theselayers may be patterned even though it is not mentioned. Patterning isonly mentioned for those layers where a pattern is a must. If asubstrate is used with a preprinted transparent or another conductorthen the first step of printing the conductive layer can be eliminated.Optional layer(s) are indicated, as sometimes the previous layer canprovide a dual functionality, e.g., a layer can act as an electrode andas an encapsulation layer. If a porous substrate is used (e.g., porousfabric or a porous paper), then it may need an optional blocking layerto block the pores, unless the first functional layer going on this alsoblocks the pores. Back and front refers to the layer sequencing as theyappear from the viewing direction. The drying or curing steps betweeneach layer is needed and assumed and is not mentioned below in thevarious print sequences. Some examples of print sequences for printabledevices with an electrolyte and the EC layer combined in a single layerare given below. In the examples below it is assumed that when onestarts with a transparent substrate as the first layer then the deviceis viewed through this substrate, and when an opaque substrate is usedthen it is viewed from the top. The substrate or the other coatings mayalso be given an optional surface treatment to enhance the wettabilityand the adhesion of the next layer. Some of these treatments are coronadischarge, flame and plasma treatment (e.g., see processes and equipmentfrom Lectro Engineering, St. Louis, Mo.). Another surface treatment usesUV-ozone, e.g., OAI Inc (San Jose, Calif.) supplies equipment andprocesses for such a treatment.

Printable device 1 on a transparent substrate: (a) print transparentconductor, (b) print EC layer, (c) print back electrode and (d) printoptional encapsulation layer.

Printable device 2 on a transparent substrate: (a) print transparentconductor, (b) print patterned insulator, (c) print EC layer, (d) printback electrode and (e) print optional encapsulation layer.

Printable device 3 on a transparent substrate: (a) print transparentconductor, (b) print patterned insulator, (c) print EC layer, (d) printpatterned insulator (e) print back electrode and (f) print optionalencapsulation layer.

Printable device 4 on a transparent substrate: (a) print transparentconductor, (b) print EC layer, (c) print patterned insulator (d) printback electrode and (e) print optional encapsulation layer.

Printable device 5 on an opaque substrate: (a) print back conductor, (b)print EC layer, (c) print transparent electrode and (d) print optionalencapsulation layer.

Printable device 6 on a opaque substrate: (a) print back conductor, (b)print EC layer, (c) print patterned insulator (d) print fronttransparent electrode and (e) print optional encapsulation layer.

Printable device 7 on an opaque substrate: (a) print back conductor, (b)print patterned insulator, (c) print EC layer, (d) print patternedinsulator (e) print transparent electrode and (f) print optionalencapsulation layer.

Printable device 8 on an opaque substrate: (a) print back conductor, (b)print EC layer, (c) print patterned insulator (d) print transparentelectrode and (e) print optional encapsulation layer.

In all of these devices, there is a common thread, which is that theelectrolyte layer which is also the electrochromic layer is printedi.e., it is printable on electrodes and in addition, the other layersincluding electrodes can be printed on this electrolyte or theelectrochromic layer. This allows one to form devices with opposingelectrodes on different planes rather than being only printable when aninterdigited device with both electrodes on the same plane is made.Interdigited devices have limitations in terms of the types of displaysand the information that can be displayed. An important reason in thepast for making interdigited electrode has been the difficulty indepositing the top electrode on top of the electrolyte layer. However,this invention discloses solid electrolytes that have good mechanicalproperties, form good adhesion and can be formulated with electrolyticcomponents as processable materials. This allows other layers to beprinted on such layers. Further, the processability of the electrolyticor the EC layer is not different from the processability of the otherlayers with similar viscosity. This is not true for the other EC devicesin the market today that use the opposing electrodes in a differentplane. These devices require sandwiching of the electrochromic and/orthe electrolyte layer in between two distinct substrates, even thoughthese are called printable devices because some of the layers areprinted, but the final assembly then requires lamination. Field devicessuch as liquid crystal and electrophoretic devices either require anelectrochromic layer to be fabricated with high precision which is thenlaminated, or require special lines to process displays where thematerial is embedded between two substrates. This leads to expensivemanufacturing due to the need for bringing electrodes from bothsubstrates into a common plane to interface with the electronics, andalso the need for edge sealing. In other EC devices either theelectrolytes or the EC layers are gelatinous or have properties thatthey also require a lamination with another substrate, even though thespecific layers are printable (e.g., see PCT application WO09000547 andU.S. Pat. No. 6,879,424). The mechanical properties of the electrolytelayer are often poor and to keep the device intact, edge sealing isneeded. The devices of this invention can be made so that all layers areassembled by a sequential printing process using continuous standardequipment (roll to roll or on discrete substrates, rigid or flexiblesubstrates). Further, since hydrophobic materials are used in theelectrolyte and/or the electrochromic layers, these do not requireexpensive containment in an inert atmosphere during processing. Theselection of the material for the electrolyte (or ion conduction layer)is the key in being able to print this layer and be able to print otherlayers on top of it. Some EC devices may comprise redox layers inaddition to the electrolyte layer (or ion conduction layer) andelectronically conductive electrodes, which can all be printedsequentially to make a completely printable device without the use of alamination step. Printing processes are those that are commonly used bythe industry including offset lithography, engraving, ink-jet,thermography, printing with molten liquids (including laser printingthat uses solid toner that is fused on to the substrate by heating),reprographics, digital printing, letterpress flexography, gravure andpad printing. There may be other methods employed which are extensionsand modifications and combinations of these. In addition, the differentlayers of a device may use the same or different printing methods orheads on a device manufacturing line.

EXAMPLE 1

TABLE 1 Electrolyte formulation Material Quantity BMP-NTF 1.5 ml SOLEF21216/1001 0.20 g SOLEF 11008/1001 0.17 g Acetone 4 ml TiO₂ (TiPureDuPont 0.4 g R960W28) 2,2′-Bithiophene 0.166 g Diethylviologen NTF 0.158g

The electrolyte was prepared by adding the two fluorinated polymers(Solef polymers from Solvay Solexis, Thorofare, N.J.) to a sure sealbottle fitted with stir bar. To this was added the acetone (ACS grade)and the bottle sealed and stirred rapidly at room temperature forapproximately two hours until a slightly hazy clear mixture wasobtained. The ionic liquid (NTF salt of 1-butyl-3-methyl-pyrrolidium,also called BMP-NTF) addition was then followed by 2-2′bithiophene. Thesolution was stirred for approximately 30 minutes and then the viologenadded. The mixture was stirred for 15 minutes and then the TiO₂ addedand again stirred for 15 minutes. If the stirring is stopped the TiO₂powder settles to the bottom of the flask and can be redispersed bystirring. Thixotropic additives such as fumed silica may be also added.

The electrolyte was spin coated onto half wave ITO at 400 rpm for 60seconds and then at 1000 rpm for 60 seconds. This resulted in an offwhite thin film approximately 11 microns thick. The electrolyte coatedITO substrate was left to solidify at room temperature under slightvacuum (4″ Hg) for 2 hours (solidification occurred by crystallizationof the Solef polymers). Then a second ITO substrate was placed on top ofthe electrolyte and the two substrates held together with binder clips.The cell was activated at 2.0 volts and immediately went from white to adark blue color and when shorted turn pink-brown in color. The bluecolor faded with time, and pink-brown color was permanent due to theformation of a polymeric film at the anode. The color coordinates(X,Y,Z) of the cell at various stages is given below (measured at anincident angle of 10 degrees)

TABLE 2 Sample State X Y Z Clear 50.4 54.1 52.2 Shorted (immediately)10.8 10.5 10.5 Steady state 29.7 26.0 15.5

EXAMPLE 2

TABLE 3 Electrolyte formulation Material Quantity BMP-NTF 1.5 ml SOLEF21216/1001 0.274 g SOLEF 11008/1001 0.17 g Acetone 4.8 ml TiO₂ (TiPureDuPont 0.8 g R960W28) 3,4 Dimethoxythiophene 0.144 g Diethylviologen NTF0.155 g

The above electrolyte was prepared using the same ionic liquid as inExample 1. A coating was deposited using a doctor blade in a thicknessof about 80 microns (wet thickness) on an ITO coated glass substrate.After drying at room temperature for about 5 minutes it was subjected tovacuum for a similar period for further drying. A gold coated polyesterfilm about 10 microns in thickness (14 ohms/square and visibletransmission of 74%) was placed on its back and pressed to form theother electrode. After 2V was applied for 10 seconds followed byshorting of the two electrodes for about a second, the device turneddeep blue, and after the color of the viologen faded away, the film thatformed was light blue in color.

EXAMPLE 3

TABLE 4 Electrolyte formulation Material Quantity BMP-NTF 1.5 ml SOLEF21216/1001 0.444 g Acetone 4 ml TiO₂ (TiPure DuPont 0.8 g R960W28)2,2′-Bithiophene 0.166 g Diethylviologen NTF 0.155 g

The above electrolyte was prepared using the same ionic liquid as inExample 1. A coating was deposited using a doctor blade in a thicknessof about 80 microns (wet thickness) on an ITO coated glass substrate.After drying at room temperature for about 5 minutes it was subjected tovacuum for a similar period for further drying. A gold coated polyester(14 ohms/square and visible transmission of 74%) film was placed on itsback and pressed to form the other electrode. The thickness of the goldfilm was ten microns. 2V was applied for 10 seconds and then shorted fora second, the device turned the same color as in example 1, and afterthe color of the viologen faded away, the film that formed was similarto the one in Example 1 in color.

EXAMPLE 4

TABLE 5 Electrolyte formulation Material Quantity BMP-NTF 1.5 ml SOLEF21216/1001 0.444 g Dimethylformamide 4.8 ml TiO₂ (TiPure DuPont 0.8 gR960W28) 2,2′-Bithiophene 0.166 g Diethylviologen NTF 0.155 g

The above electrolyte was prepared using the same ionic liquid as inExample 1. A coating was deposited using a doctor blade in a thicknessof about 80 microns (wet thickness) on an ITO coated glass substrate(about 15 ohms/square). After drying in an oven at 90° C. for 15minutes, the coating was subjected to a vacuum for 5 minutes to removethe solvent. A gold coated polyester (14 ohms/square and visibletransmission of 74%) was placed on its back and pressed to form theother electrode. 2V was applied for 10 seconds and then the electrodeswere shorted, the device turned the same color as in example 1, andafter the color of the viologen faded away, the film that formed wassimilar to the one in Example 1 in color.

EXAMPLE 5

TABLE 6 Electrolyte formulation Material Quantity BMP-NTF 1.5 ml SOLEF21216/1001 0.444 g Acetone 4.8 ml TiO₂ (TiPure DuPont 0.8 g R960W28)2,3′-Bithiophene 0.166 g 3,4 Dimethoxythiophene 0.144 DimethylviologenNTF 0.155 g

The above electrolyte was prepared using the same ionic liquid as inExample 1. The electrolyte coating was deposited using a doctor blade ina thickness of about 80 microns (wet thickness) on an ITO coated glasssubstrate (about 15 ohms/square). After drying in an oven at 90° C. for15 minutes, the coating was subjected to a vacuum for 5 minutes toremove the solvent. A gold coated polyester (14 ohms/square and visibletransmission of 74%) was placed on its back and pressed to form theother electrode. 2.5V was applied for 5 seconds and then shorted for afew seconds, the device initially appeared green, however when theviologen color faded away in a few minutes only yellow color remained.

EXAMPLE 6

TABLE 7 Electrolyte formulation Material Quantity BMP-NTF 1.5 ml SOLEF21216/1001 0.444 g Acetone 4.8 ml TiO₂ (TiPure DuPont R960 0.8 g W28)3,4 Ethylenedioxythiophene 0.142 Diethylviologen NTF 0.155 g

The above electrolyte was prepared using the same ionic liquid as inExample 1. The electrolyte coating was deposited using a doctor blade ina thickness of about 80 microns (wet thickness) on an ITO coated glasssubstrate (about 15 ohms/square). After drying in an oven at 90° C. for15 minutes, the coating was subjected to a vacuum for 5 minutes toremove the solvent. A gold coated polyester (14 ohms/square and visibletransmission of 74%) was placed on its back and pressed to form theother electrode. 2.5V was applied for 5 seconds and then shorted for afew seconds, once the viologen color faded away in a few minutes onlyblue color remained.

EXAMPLE 7

A display device was prepared where one REDOX couple was a solid thinfilm of poly(3,4-ethylenedioxythiophenepolystyrenesulfonate) (PEDOT) andthe other a solution of the monomer 2,2′-bithiophene.

The device was composed of two electrodes of 12′Ω/sq ITO on glass. Oneelectrode was coated with a coating of 3,4-PEDOT by spin depositing at500 rpm from a solution of “Baytron P” supplied by H.C. Starck Inc,Newton, Mass. After deposition, the coating was dried at 130° C. for 15minutes and had a thickness of 285 nm. This electrode had a slight bluetint. The electrolyte was prepared by dissolving 0.5 molar2,2′-bithiophene in 1-butyl-1-methylpyrrolidiumbis(trifluoromethylsulfonyl)imide. This electrolyte was placed betweenthe “Baytron P” coated electrode which formed the anode and an ITOcoated electrode which formed the cathode. The electrolyte thickness orcell gap was 75 μm. The cell was powered by applying a known potentialacross the cell (negative to the “Baytron P” electrode) and by shortingthe electrodes. This cell had three states. The first state with a clearstate of 75% transmission at 650 nm when no power is applied, the secondstate is when power is applied and the 2,2′-biothophene monomerpolymerized at the cathode forming a coating and the PEDOT was reducedgiving a blue color, the third state was when the cell was shorted (theopposing electrodes are shorted) the PEDOT oxidized and thepolythiophene coating (reduced) to give a cell with an orange browncolor. After the cell was taken through the three stages describedabove, the cell after having been shorted was subjected to 2V, with thePEDOT side of the electrode being negative. The active area of the cellwas 1.1 square inches and the time to change transmission from 73 to 55%T was 0.4 seconds. Then the cell was again shorted and then varyingpotentials in incremental steps were applied as shown Table 1 (PEDOTside being negative). The color and transmission at 650 nm at each stepare also shown in this table. This would correspond to stage 2 for eachpotential, where various stages are described in Example 8.

TABLE 8 % transmission and color of device at different potentials %Transmission at Potential (volts) (650 nm) Color of display 0.0 73Orange Brown 0.5 72 Orange Brown 1.0 66 Purple/Orange 1.5 58 Blue 2.0 55Blue 2.4 51 Blue

EXAMPLE 8

A transparent cell was prepared exactly as described in Example 7 abovewith an active area of 1.0 square inches (the active area was almost ina shape of a square). The cell was first activated at 2.0 volts for 20seconds (PEDOT side being negative) and then shorted and again activatedat 2.0 volts (PEDOT being negative) the kinetic trace for thisactivation at 650 nm is shown in the FIG. 11. At 650 nm the cell had aninitial % T of 75 and applying 2.0 volts for 20 seconds the transmissiondropped to 48%. It can be seen that for each activation after the firsttime, the change is rapid.

The color coordinates of the cell were recorded in the initial stage(stage one) and after applying potential (2.0 volts) stage two (most ofthe color comes from PEDOT coating) and when shorted stage three (mostof the color comes from polybithiophene coating). The data is shown inTable 9.

TABLE 9 Color Coordinates of Display XYZ coordinates at 10° using D65lamp Display State X Y Z Stage 1 74.35 80.25 83.32 Stage 2, colored 2.056.47 60.98 66.99 volts (blue to eye) Stage 3, shorted (red- 64.75 66.6364.84 brown to eye)

A similar cell was prepared as above, however, the electrolyte wasloaded with titanium dioxide powder (Dupont's R960) to make theelectrolyte opaque in order to see the reflected coloration on each sidewithout interference from the other side. In the powered state, thePEDOT side was deep blue and the other side was colorless. In theshorted state, the PEDOT side was faint blue, and the other side wasred-brown.

EXAMPLE 9

A cell was prepared as described in example 1 with the exception that athin film of tungsten oxide (WO₃) was used instead of3,4-polyethylenedioxythiophenepolystyrenesulfonate. The tungsten oxidecoating was deposited onto ITO, from a solution of peroxotungstic esterin ethanol, by spin coating at 1000 rpm. The peroxotungstic estersolution was prepared as given in example 1 of U.S. Pat. No. 5,457,218.The coating was cured at 130° C. for 15 minutes and had a thickness of230 nm. This curing condition was chosen as this may be used to heattreat an ITO coated, heat stabilized polyester film to make this deviceon plastic substrate. The resulting electrode was colorless.

A cell was prepared using the WO₃ electrode as described in example 1and activated at 2.0 volts with the negative charge to the WO₃ electrodeand shorted to result in a color change.

The cell was clear after preparation and when activated at 2.0 volts itturned deep blue and when shorted turned purple. The color coordinatesof the cell at the different stages is shown in Table 10.

TABLE 10 Color coordinates of tungsten oxide cell with 2,2′-bithiophenein IL XYZ 10°/D65 Comments X Y Z Color Cell in clear state 74.61 78.6281.08 Clear and (as prepared) Colorless Cell in blue state (WO3 24.4426.12 34.25 Blue colored) Cell in purple state 21.49 20.48 28.29 Purple(polymer film deposited)

EXAMPLE 10

A cell was prepared using a transparent electrolyte as described inExample 7 except that a thin film of polyaniline was used as theoxidant. The polyaniline was deposited onto ITO by spin coating at 5000rpm. The coating solution was composed of 0.6012 g of polyanilineemeraldine base in 20 ml of formic acid. The coating was lightblue/green in color. The cell was activated at 2.0 volts such that thepolyaniline is reduced and the bithiophene is oxidized. At 550 nm thecell changed color from blue/gray at 2.0 volts to brown/orange whenshorted. Going from blue/gray to brown/orange resulted in an opticalmodulation of 13% T at 550 nm. The time to change color was 0.5 seconds.If instead of a transparent electrolyte an opaque electrolyte (e.g.,those comprising titania) is used, only the colors of each electrodesare visible from the side the cell is observed, as would be the case inmost display cells.

EXAMPLE 11 Device Using PEDOT as the Transparent Conductor

A display device was prepared as shown in FIG. 4. The transparentconductor (43 and 40) was a coating of3,4-polyethylenedioxythiophenepolystyrenesulfonate (Baytron P or PEDOT)supplied by H.C. Starck Inc, Newton, Mass. This was deposited onto athin polyester substrate (44) by spin coating initially at 200 rpm andthen accelerating to 1000 rpm in a period of 30 seconds and then keepingthe spin speed to 1000 rpm for 30 seconds. The coating was then heatedat 90° C. for 10 minutes. This procedure was repeated once more to givea conductive coating of approximately 1000′Ω/sq. This coating wasscribed with a blade down the center to give two distinct conductiveregions 43 and 40 on the polyester substrate. The separation between thetwo conductive regions was approximately 0.04 mm. This substrate wascoated using a doctor blade with an electrolyte (42) composed of 0.5M2,2′-bithiophene, 0.1M diethyl viologenbis(trifluoromethylsulfonyl)imide, 28 wt % 1-butyl-1-methylpyrrolidiumbis(trifluoromethylsulfonyl)imide, 6 wt % of a fluorinated copolymer(Solef PVDF 21216 supplied by Solvat Solexis USA) 11 wt % TiO₂ particles(Ti-Pure R960 W28 supplied by DuPont USA) and 51 wt % acetone. Thedeposited electrolyte was dried at room temperature for approximately 15minutes. This was then covered (41) with a white adhesive backing tape(Venture Tape supplied by Rockland, Mass. USA).

The display was powered by applying two volts across the planartransparent conductors via terminals 45 and 46. This resulted in a welldefined red/orange line about 0.1 mm in width down the center of thedevice (adjacent to the scribed line on the positive side) due to theelectrochemical polymerization of 2,2′-bithiophene at the negativeelectrode. Simultaneously on the other side (cathode or the negativeside) a blue color line was formed due to the reduction of viologen thatfaded with time, however the orange blue line remained permanently. Theformation of temporary blue line provided additional contrast. Byswitching the potential the width of the red/orange line could beincreased due to polymerization of 2,2′-bithiophene on the other side ofthe scribed line as the above process was repeated in reverse. For astrip (scribe) length of 2.3 cm the polymerization time at 2 volts wasbetween 0.5 and 3 seconds. Once the cell is activated the red/orangestrip is permanent and is non reversible. In this example PEDOT may beremoved chemically or by abrasion. Also PEDOT may be printed so that thedeletion line is part of the print pattern.

EXAMPLE 12 Device where PEDOT is Used as TC and Redox Couple

A device was prepared as described in example 11 except that the3,4-polyethylenedioxythiophenepolystyrenesulfonate conductive electrodewas also used as the Redox couple for the 2,2′-bithiophenepolymerization. In this case the electrolyte was prepared without theaddition of diethyl viologen bis(trifluoromethylsulfonyl)imide. At anapplied potential of 2.0 volts the 2,2′-bithiophene polymerized on thenegative electrode at the junction between the two planar transparentconductors. The time to deposit red/orange polymeric coating was between5 and 10 seconds.

EXAMPLE 13 Device where PEDOT is Used as Redox couple and ITO as TC

A device was prepared as described in example 12 except that the3,4-polyethylenedioxythiophenepolystyrenesulfonate was deposited on topolyester coated with ITO with a sheet resistance of 50′Ω/sq. For thisdevice the role of 3,4-polyethylenedioxythiophenepolystyrenesulfonate(PEDOT) was to act as a Redox couple to the polymerization of2,2′-bithiophene and not a transparent conductor. When 2.0V volts wereapplied to this device the polymerization was within 0.5 to 3 secondswith a well defined red/orange strip down the center of the device.

EXAMPLES 14 Device without PEDOT and Using ITO as TC

A device was prepared as described in example 11 where 50′Ω/sq. ITO onpolyester film was used as the transparent conductor instead of3,4-polyethylenedioxythiophenepolystyrenesulfonate (PEDOT). The devicewas activated at 2.4 volts for 5 seconds and had a peak current of 94 μAto color a line which was 2.3 cm long (or 4 mA/cm² based on the coloredarea). The peak current decreased to about 80% of its peak value inabout 5 seconds. It was also observed that with increasing poweringtime, the width of the colored regions increased (almost 1 mm widepolymerized thiophene in 60 seconds). This electrolyte had highconductivity, and in some cases even if the width of the etched line was1 cm wide, both side of the etched regions colored rapidly (one sidepermanently due to 2,2′-bithiophene and the other side temporarily dueto viologen).

EXAMPLE 15 Information Printed Using Insulating Material

A device was prepared where the transparent conductors were 12′Ω/sq. ITOon glass. On the first substrate with ITO coating (the cathode) numbersand letters were placed by a contact adhesive method in order to maskthe conductive areas. These letters and numbers along with the adhesivewere electrically insulating.

An electrolyte was prepared consisting of 0.5M 2,2′-bithiophene, 0.1Mdiethyl viologen bis(trifluoromethylsulfonyl)imide,1-butyl-1-methylpyrrolidium bis(trifluoromethylsulfonyl)imide and 16.5wt % TiO2. Then a second ITO conductive glass substrate was placed ontop of the electrolyte in order to sandwich the electrolyte between thetwo conductive sides. The electrolyte thickness was 75 μm. The lettersand numbers (masked areas on the first ITO) were not visible as onelooked into the sample through the second substrate. This means that inthe off state the device was white with no visible numbers or letters. Apotential of 2.0 volts was applied across the cell such that the cathodewas the ITO electrode with the numbers and letters. On application ofthe potential within 0.5 to 3 seconds the device turned from white to anorange/red background with the numbers and letters appearing incontrasting white, i.e., the electrolyte in these areas did not changecolor. A similar device was made where the letters were printed using alaser printer using a black toner on the ITO coated polyester thusmasking the ITO locally. This device functioned in the same fashion.

EXAMPLE 16 Writing Letters with Electrochemically Active Material

A device was prepared where the transparent conductors were 12′Ω/sq. ITOon glass. On first ITO surface (the cathode) letters were painted usinga solution of 3,4-polyethylenedioxythiophenepolystyrenesulfonate(Baytron P or PEDOT) supplied by H.C. Starck Inc, Newton, Mass. Anelectrolyte was made using 0.5M 2,2′-bithiophene in1-butyl-1-methylpyrrolidium bis(trifluoromethylsulfonyl)imide and 16.5wt % TiO2. For this device the printed3,4-polyethylenedioxythiophenepolystyrenesulfonate on the cathodeelectrode acts as a redox couple to the polymerization of2,2′-bithiophene at the anode. The electrolyte was deposited on thefirst electrode and then a second ITO coated substrate was lowered tosandwich the electrolyte which had a thickness of 75 μm. In the offstate the device was white with no visible letters, when viewed from thesecond substrate. On application of a potential of 2.0 volts immediately(within 0.5 to 3 seconds) the device turned color with the lettersappearing as orange/red. The letters only appeared in the regions of theanode which were directly above the printed3,4-polyethylenedioxythiophenepolystyrenesulfonate letters.

EXAMPLE 17 Example of a Reversible Display

A display device was prepared using 50′Ω/sq. ITO on polyester. Using ablade a ridge was cut down the center of the substrate isolating theconductive ITO into two planar electrodes. The ridge was approximately30 μm wide and 2.5 cm long. An electrolyte was prepared which wascomposed of an electrochromic bridged dye and had the followingcomposition; 28 wt % 1-butyl-1-methylpyrrolidiumbis(trifluoromethylsulfonyl)imide, 0.5M of bridged dye, i.e., 1-(4ferrocenylbutyl)-1′-methyl-4,4′ bipyridinium1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide] salt, 6wt % of a fluorinated copolymer (Solef PVDF 21216 supplied by SolvaySolexis USA), 11 wt % TiO₂ particles (Ti-Pure R960W28 supplied by DuPontUSA) and 51 wt % acetone. The electrolyte was coated on the ITO scribedsubstrate using a doctor blade and dried at room temperature. The devicewas powered by applying 2.0 volts across the two planar ITO electrodes.Immediately (1 to 3 seconds) a deep blue line appeared across thescribed line dividing the ITO electrodes. The power was removed and theline remained visible for 60 seconds. This was repeated many times andeach time the same performance was seen giving a reversible display. Theonset voltage was 0.7 volts.

EXAMPLE 18 Formation of Characters Using Two Interdigited Electrodes

FIG. 9 shows the schematics of a display formed using interdigitedprinciples. When powered this display will reveal “AMER”. This shows asubstrate with a conductive transparent coating, say ITO. All the lines(excepting the hashed lines) are etched. One way to do that is by laseretching and the lines may be about 10 to 100 microns wide. Laser etchingcan be done by standard procedures by commercial vendors (e.g., Laserodof Torrance Calif.). When the laser etching along the solid lines asshown in this figure are done, the pattern is divided in three regions90, 91 and 92. One side of all of the letters are contiguously connectedto 91 and the other side of the etched letters to 92, which form the twoelectrodes. The areas 90 are bounded by the contiguous ITO regions 91and 92 but the physical separation between the two electrodes is muchlarger then those regions which are only separated by the width of thelaser etched lines. To make a device all of this is coated with a layerof the electrolyte leaving small areas of uncoated 91 and 92 (not shown)which can be connected to the powering leads. When the leads arepowered, the two sides of the etched ITO start to color along the etchedline where the separation between the electrodes is smaller. Theboundaries of area 90 do not color as the opposite polarity electrodesare too far apart. If the electrolyte conductivity is high and theboundaries of the large regions also color, one can optimize theelectrolyte conductivity so that only the desired areas color. Anothermethod to only color specific areas is to coat part of the device withthe electrolyte pattern, and fill in the gaps within this pattern usinga color matched non-electrolytic layer. The electrolyte layer will beput down in a pattern so that it touches both the electrodes where theyare separated by the narrow distance, and the rest is occupied by thecolor matched layer. The electrolyte coating over the characters (ornarrow lines just touches the inert insulating layers or even slightlyoverlaps them. This allows the electrolyte continuity to be broken. Whenthe electrolyte composition is as in Example 11 then the display isirreversible due to the polymerization of the thiophene, and if it issimilar to Example 17 then it is reversible. Since the coloration startsat the etched lines and proceeds inwards (meaning towards the regionhaving the transparent conductor) with time, one can control their widthwith time, i.e., at short powering times, power consumption is less andthe line width is also small.

EXAMPLE 19 Electrolyte with Improved Adhesion

An Electrolyte was prepared as follows in a sure seal bottle. Solef21216/1001 (1.0 g), a polyvinylidene fluoride polymer, was mixed withpolymethylmethacrylate, (mw=15,000) (1.0 g) in 4.8 ml propyl acetate byslowly stirring (max. speed of 280 RPM) on a magnetic stirrer at roomtemperature for at least 2 hours or until well mixed. Then the followingwere added: 2.92 ml of the ionic liquid 1-butyl-1-methylpyrrolidiniumbis(trifluoromethylsulfonyl)imide (2.92 ml), 0.2M Ferrocene ViologenImide Dye (0.5680 g) and TiO₂ (Ti-pure R960 from Dupont, coated withalumina and silica) (1.8 g). These were mixed in by slowly stirring(max. speed of 280 RPM) on a magnetic stirrer at room temperature for atleast 1 hour or until well mixed. Finally, fumed silica (0.2 g) (fromSigma-Aldrich, Milwaukee, Wis., product 38, 126-8) was added and thesolution was again stirred slowly (max. speed of 280 RPM) on a magneticstirrer at room temperature for at least 30 minutes or until well mixed.This electrolyte was an opaque, off-white liquid. The viscosity wasdetermined to be 48.5cP at 27.8° C. using a Brookfield model DV-III+viscometer with a cone and plate attachment. PMMA is not compatible withthe ionic liquid, however, Solef polymer is compatible.

This electrolyte was used to make an EC device using interdigited TTOelectrodes as follows. ITO (about 60 ohms/square) was obtained onflexible 250 micron thick polyester (PET). An image of an “X” was formedon the ITO by scoring with a razor blade which cut the ITO coating infour segments without cutting through the substrate. The size of each ofthe four arms of the “X” was about 1.1 cm. The electrolyte was doctorbladed onto the ITO to give a wet thickness of ˜260 μm. This coating wasthen dried at 50° C. for 15 minutes to give a tacky, off-white coatingof ˜90 μm thickness. This coating was then covered with white adhesivetape for encapsulation. The cell was powered at 2 volts with eachadjacent quadrant being of opposite polarity, and the image of the “X”appeared (along the score lines on the negative side) in about 1 secondin a deep blue color. This device was left at room temperature for 72hours after which no significant change in performance was seen.

Another device was made with the same electrolyte by sandwiching theelectrolyte between two conductive ITO coated polyesters with thesubstrate characteristics described above. The electrolyte was doctorbladed onto the ITO on first substrate to give a wet thickness of ˜260μm. This coating was then dried at 50° C. for 15 minutes to give atacky, off-white coating of ˜90 μm thickness. The electrolyte coatingwas sprinkled with a small amount of 88 μm spacer beads, was coveredwith a second piece of ITO on PET, such that the electrodes wereslightly offset, and was then pressed together to give a cell that wasabout 1.25″×1.25″. The cell was powered at 2 volts and the negativeelectrode changed from off-white to deep blue in about 2 seconds. Thiscell was not encapsulated. It was left at 80° C. for 22 hours and thenat 50° C. and 75% relative humidity for 17 hours. After this time, nosignificant change in performance was noted.

Another device was made using glass substrates coated with ITO (12Ω/□).The electrolyte was doctor bladed onto the ITO to give a wet thicknessof ˜260 μm. This coating was then dried at 50° C. for 15 minutes to givea tacky, off-white coating of ˜90 μm thickness. The electrolyte coatingwas sprinkled with a small amount of 88 μm spacer beads, was coveredwith a second piece of ITO on glass and was then pressed together togive a cell that was about ⅞″×⅞″. This cell was encapsulated by applyinga UV cured acrylic adhesive at the perimeter. The cell was powered at 2volts and changed from off-white to deep blue in about 2 seconds. It wasleft at 80° C. for 22 hours and then at 50° C. and 75% relative humidityfor 17 hours. After this time, no significant changes in performance orcosmetics were seen.

EXAMPLE 20 Electrolyte and Devices Incorporating Polyurethane Matrix

A polyurethane comprising electrolyte was prepared as follows in a sureseal bottle. A thermoplastic polyurethane (PUL446-107, from HuntsmanChemical, The Woodlands, Tex.). This urethane is based on an aliphaticisocyanate and a polyether glycol. 0.5 g polyurethane (PU) was dissolvedin 6 ml tetrahydrofuran (THF) by stirring on a magnetic stirrer at roomtemperature for several hours or until well dissolved. Then ionic liquid(IL), 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide,(0.73 ml), 0.2M Ferrocene Viologen Imide Dye (0.142 g) and TiO₂ (Ti-pure8960 from Dupont,) (0.45 g) were also mixed in by stirring on a magneticstirrer at room temperature for at least 1 hour or until well mixed. THFsolubilizes both the urethane and the electrolytic materials, but theurethane polymer is not compatible with the electrolyte. Finally, fumedsilica (0.05 g, same material as in Example 19) was added and thesolution was again stirred on a magnetic stirrer at room temperature forat least 30 minutes or until well mixed. This electrolyte was an opaque,off-white liquid. The electrolyte was made into two differentelectrochromic cells, one with an interdigited structure and the secondwhere the back electrode was a printed carbon electrode.

The interdigited construction is similar to the one described in Example19. The surface of ITO coated PET was scored using a razor blade in ashape of “X”. The ITO was 60Ω/□ on PET. The electrolyte was doctorbladed onto the ITO to give a wet thickness of ˜260 μm. This coating wasthen dried at 50° C. for 15 minutes to give a dry, off-white coating of˜90 μm thickness. This coating was then covered with white adhesivebacking tape for encapsulation. The cell was then powered at 2 volts andthe image of the “X” was such that it divided the planar ITO into twohalves forming an anode and cathode. After one second of appliedpotential the white surface changed from one with a dark blue “X” imagewith a white background. Upon shorting the device the dark blue “X”image immediately disappeared to give a white surface. This device wasleft at 85° C. for 24 hours upon which no significant change inperformance was noted.

The electrolyte was made into an EC device by sandwiching theelectrolyte between a glass/ITO electrode and an electrode formed bycarbon paste. The ITO resistivity was 12Ω/□ on Glass. The electrolytewas doctor bladed onto the ITO to give a wet thickness of ˜260 μm. Thiscoating was then dried at 50° C. for 15 minutes to give a dry, off-whitecoating of ˜90 μm thickness. On this electrolyte coating was then doctorbladed a conductive carbon paste (Product #5065) from SPI (West Chester,Pa.) with a wet thickness of ˜160 μm as seen through the glasssubstrate. The cell was then dried at 50° C. for 10 minutes. The cellwas powered at 2 volts and changed from off-white to deep blue in about2 seconds.

EXAMPLE 21 Electrolyte with Both PU and Acrylic Polymer

A polymer blend electrolyte was prepared as follows in a sure sealbottle. Polyurethane (PUL446-107) (0.4 g) was mixed with 0.1 gpolymethylmethacrylate (PMMA, mw=15,000) in 6 ml tetrahydrofuran (THF)by stirring on a magnetic stirrer at room temperature for several hoursor until well dissolved. Then ionic liquid (IL),1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (0.73ml), 0.2M Ferrocene Viologen Imide Dye (0.142 g) and TiO₂ (Ti-pure 8960from Dupont) (0.45 g) were also mixed in by stirring on a magneticstirrer at room temperature for at least 1 hour or until well mixed. Inthis system the acrylic polymer is not soluble in the ionic liquid.Finally, fumed silica (0.05 g) was added and the solution was againstirred on a magnetic stirrer at room temperature for at least 30minutes or until well mixed. This electrolyte was an opaque, off-whiteliquid. The electrolyte was used to make a interdigited electrochromicdevice as described in Example 20. After drying the electrolyte appearedtacky. The cell when powered at 2 volts displayed a dark blue “X” inabout one second with a white background and when shorted immediatelybleached to a plain white background.

EXAMPLE 22 Electrolyte and Devices Incorporating Polyurethane Matrix

A polyurethane electrolyte was prepared as follows in a sure sealbottle. Polyurethane (see Example 20) (0.5 g) was dissolved in 4 mlmethyl sulfoxide (99.9% from Sigma Aldrich Chemical CO.) by stirring ona magnetic stirrer at room temperature for several hours or until welldissolved. Then ionic liquid (IL), 1-butyl-1-methylpyrrolidiniumbis(trifluoromethylsulfonyl)imide, (0.73 ml), 0.2M Ferrocene ViologenImide Dye (0.142 g) and TiO₂ (Ti-pure 8960 from Dupont,) (0.45 g) werealso mixed in by stirring on a magnetic stirrer at room temperature forat least 1 hour or until well mixed. Finally, fumed silica (0.05 g) wasadded and the solution was again stirred on a magnetic stirrer at roomtemperature for at least 30 minutes or until well mixed. Methylsulfoxide solubilizes both the urethane and the electrolytic materials,but the urethane polymer is not compatible with the electrolyte.

This electrolyte was an opaque, off-white liquid. The electrolyte asdescribed was made into an electrochromic cell with interdigitedelectrodes as described in Example 20. Substrates size and conditionswere similar to Example 20 unless mentioned differently in the currentexample. This wet electrolyte coating as deposited was about 260 μm andwhen dried at 85° C. for 15 minutes it give a dry, off-white coating of˜90 μm thickness. This coating was then covered with white adhesivebacking tape for encapsulation. The cell was then powered at 2 volts anda blue image of the X within a second along the scored lines. Uponshorting the device the dark blue X image immediately disappeared togive a white surface. This device was left at 85° C. for 24 hours uponwhich no significant change in performance was noted. Bleach kinetics ofthe cell was tested for different color times as shown in the tablebelow. The average peak current was 0.26 mA. The cell was colored at 2.0volts for 2 and 10 seconds and in shorted mode took 3 and 9 seconds tobleach respectively.

Color Time (seconds) Bleach time (seconds) at 2.0 volts in open circuit2 7 4 10 6 20 8 27 10 33

EXAMPLE 23 Electrolyte and Devices Incorporating Polyurethane Matrix

A polyurethane comprising electrolyte was prepared as follows in a sureseal bottle. A thermoplastic polyurethane (PUL446-107, from HuntsmanChemical, The Woodlands, Tex.). This urethane is based on an aliphaticisocyanate and a polyether glycol. 0.5 g polyurethane (PU) was dissolvedin 4 ml methyl sulfoxide (DMSO) by stirring on a magnetic stirrer atroom temperature for several hours or until well dissolved. Then ionicliquid (IL), 1-butyl-1-methylpyrrolidiniumbis(trifluoromethylsulfonyl)imide, (0.73 ml), 0.2M Ferrocene ViologenImide Dye (0.142 g) and TiO₂ (Ti-pure R960 from Dupont,) (0.45 g) werealso mixed in by stirring on a magnetic stirrer at room temperature forat least 1 hour or until well mixed. Finally, fumed silica (0.05 g, samematerial as in Example 19) was added and the solution was again stirredon a magnetic stirrer at room temperature for at least 30 minutes oruntil well mixed. This electrolyte was an opaque, off-white liquid. Theelectrolyte was made into an electrochromic cell where the backelectrode was a printed carbon electrode.

The electrolyte was made into an EC device by sandwiching theelectrolyte between two electrodes, one electrode being a piece ofglass/ITO and the other formed by conductive carbon paste. The ITOresistivity was 12Ω/□ on Glass. The electrolyte was doctor bladed ontothe ITO to give a wet thickness of ˜260 μm. This coating was then driedat 100° C. for 15 minutes to give a dry, off-white coating of ˜90 μmthickness. On this electrolyte coating was then doctor bladed aconductive carbon paste #8144 from DuPont Electronic Materials (ResearchTriangle Park, N.C.) with a wet thickness of 180 μm. The cell was thendried at 110° C. for 15 minutes. The cell was powered at 2 volts andchanged from off-white to deep blue in about 2 seconds and reversed whenpower was removed.

EXAMPLE 24 Device with Solvent Free Printable Electrolyte

A polyurethane based solid electrochromic layer was prepared from areactive ink using a prepolymer of aliphatic polyisocyanate (based onhexamethylene diisocyanate) from Bayer Material Science LLC with a tradename of Desmodur XP 2617 and a triol namely poly(glycerine/diethyleneadipate) glycol with a trade name Diexter-G-1100G-50 from Coim USA Inc,Deptford, N.J. This electrolyte composition did not comprise of anysolvent, and comprised of monomers that are reacted or polymerized afterprocessing to yield solid electrolyte. The reactive ink was prepared asfollows:

0.5682 g of Diexter-(G-11006-50) was added to a 50 ml plastic beaker and1.085 g of ionic liquid, 1-butyl-1-methylpyrrolidiniumbis(trifluoromethylsulfonyl)imide, added under stirring. To this wasadded 0.822 g of a ferrocene viologen imide dye and stirred until acomplete solution occurred. To this solution was added under an argonatmosphere 0.175 g of Desmodur XP 2617 and the mixture stirredvigorously. Under ambient atmosphere 0.8621 g of TiO₂ (Ti-pure 8960 fromDupont) was added and the mixture stirred until a white smooth pasteformed. To this was added 0.0006 g of the catalyst DABCO MB20 (made byAir Products, Allentown, Pa.) and the mixture stirred vigorously. Thisresulted in a viscous white paste which was doctor blade onto an ITO/PETflexible substrate and cured at 110° C. for 15 minutes. This resulted ina solid white layer with good adhesion to the underlying substrate. Atop electrode was formed on this electrochromic layer using printableconductive carbon black paste from DuPont Electronic Materials (#8144Carbon Paste) with a wet thickness of 180 μm and dried at 110° C. for 15minutes. In this case instead of a pattern the carbon ink was depositedin a solid area of about 2×2 cm. Then the active area (with electrolyteand/or the carbon paste was encapsulated using a pressure sensitive tapewith a metalized backing (in this case it had aluminum foil backing withan insulating pressure sensitive adhesive). The cell was powered at 1.2volts and changed from white to deep blue in about 2 seconds. Thedurability of the cell was tested at 75° C. for four days without anychange in the devices electrochromic performance or appearance. Anothercell was made using the same materials and procedures, however, beforethe electrolyte deposition; a clear insulating coating of a UV curablelayer was deposited on the ITO leaving areas (characters, numerals andpattern) that were not covered by this insulating layer. The electrolyteand then the carbon electrode were uniformly deposited over thesubstrate. When the device was powered, only those areas or patterncolored where the ITO was not masked by the clear insulating coating.

EXAMPLE 25 Device with Solvent Free Printable Electrolyte

A reactive polyurethane ink was prepared as described in Example 24above except that the uncured ink was deposited by a doctor blade ontoan ITO/PET substrate and a second substrate with conductive pattern (inthis case it was non-patterned ITO/PET substrate in a size of about 2×2cm) placed on top such that both substrates sandwiched the ink layerwith both ITO coatings touching the ink. In this configuration the inkwas cured at 110° C. for 15 minutes. After curing, the edges of thedevice were encapsulated using a pressure sensitive tape with polyimidebacking around all four sides. The device was activated at 1.2 volts andresulted in the white solid electrolyte layer changing uniformly to adeep blue layer (the negatively powered electrode) in about 2 seconds.When the electrodes were shorted or left in open circuit mode theelectrolyte layer returned to a white color. The durability of the cellwas tested at 75° C. for four days without any change in the deviceselectrochromic performance or appearance. Another cell was made usingthe same materials and procedures, however, before the electrolytedeposition; a clear insulating coating of a UV curable layer wasdeposited on the ITO leaving areas (characters, numerals and pattern)that were not covered by this insulating layer. The electrolyte wasdeposited on the patterned substrate and then laminated by conductiveITO coated polyester. When the device was powered (negative on the ITOelectrode where insulating pattern was deposited), only those areas orpattern colored to blue where the ITO was not masked by the clearinsulating coating. When the reverse potential was used to color thedevice (i.e. negative on the non-patterned ITO electrode), the patternfrom the back electrode appeared in color on the front electrode (whichwas not patterned). In another device the reactive electrolyte wasdeposited and partially cured on the bottom electrode before it waslaminated with the top electrode. Yet in another process variation anelectrolyte layer was deposited and cured on the bottom electrode.Another layer of electrolyte was deposited on top of the curedelectrolyte layer, cured partially and then laminated with the topelectrode. All of theses devices functioned well when powered.

EXAMPLE 26 Example of a Printable Device

A paste for depositing an electrolyte coating was prepared with thefollowing composition: 1 g PU L446-107 polyurethane; 8 ml methylsulfoxide+(with 0.1 wt % Novec FC4432 Fluorosurfactant from 3M, St.Paul, Minn.); 1.168 ml IL (1-butyl-1-methylpyrrolidiniumbis(trifluoromethylsulfonyl)imide); (0.13M) 0.1477 g ferrocene viologenimide dye; 1 g TiO2; 0.48 g fumed silica, hygroscopic. The polymer wasfirst dissolved in methyl sulfoxide, and then after adding the otheringredients, all of these were mixed for several hours using amechanical mixer until a smooth paste was formed.

A flexible film of polyester was obtained with an ITO coating so thatall of the other layers for the device can be printed. First the abovepaste was screen printed onto the ITO with a 140 mesh screen to give adry thickness of ˜16 μm electrolyte coating when dried at 110° C. for 15minutes. This electrolyte coating (with electrochromic properties) wasthen covered with a screen printed layer of conductive carbon paste#8144 from Dupont to give a dry thickness of ˜17 μm when dried at 110°C. for 15 minutes. The cell was powered at 2 volts with ITO beingnegative, and the cell colored blue as observed through the polyester.

EXAMPLE 27 Example of a Printable Device with One Redox Layer

A paste was prepared with the following composition: 2 g PU L446-107polyurethane; 8 ml methyl sulfoxide; 2.92 ml IL(1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide; 0.3124g ferrocene viologen imide dye; 0.0328 g Novec FC4432 Fluorosurfactantfrom 3M; 2.5 g TiO2; 1.2 g fumed silica, hygroscopic

This paste was doctor bladed onto a piece of polyester/ITO at a wetthickness of ˜150 μm and was then dried at 110° C. for 15 minutes toform an electrolyte layer. This electrolyte coating was further coatedwith a layer of Baytron P PEDOT solution (from HC Starck) by spincoating at a spin speed of 650 RPM. The PEDOT coating was light blue incolor and was uniform and smooth. This coating was then dried at 110° C.for 15 minutes. The polyester/ITO/electrolyte/PEDOT cell was powered at1.2 volts (ITO being negative) by touching the back of the PEDOT coatingwith a sharp conductive pin. The device colored blue (as observedthrough the polyester), but only where the pin was touching the PEDOTcoating. The PEDOT coating was then covered with a piece of conductivecarbon tape, which stuck very well to the PEDOT. The cell was againpowered at 1.2 volts and the cell completely colored blue this time.

EXAMPLE 28 Solid Electrolyte Composed of Polymer Blends

An electrolyte was prepared by first dissolving 0.34 g of polyurethane(PUL446-107) and 0.10 g of polyvinylpyrrolidone (PVP, average molecularweight 10,000) in 1.9 ml of dimethylsulfoxide (DMSO). This mixture washeated to 110° C. while stirring for one hour to form a completesolution. The mixture was cooled to room temperature and 1 ml of ionicliquid [1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide]added and 0.058 g (0.06M based on ionic liquid) of the bridged dye 1-(4ferrocenylbutyl)-1′-methyl-4,4′ bipyridinium salt with1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide]. Thiswas stirred for approximately 30 minutes until a complete solutionformed. To this solution was added 0.40 g of titanium dioxide (Ti-pure8960 from Dupont, coated with alumina and silica) and 0.19 g ofhygroscopic fumed silica which was mixed thoroughly by hand to form awhite viscous paste. The polyurethane polymer used in this exampleswells in the ionic liquid by gaining 40% weight at room temperature,showing that its one phase is compatible with the ionic liquid, and PVPis soluble in the ionic liquid showing that this is also compatible withthe ionic liquid. Further both of these polymers are soluble in theprocessing solvent DMSO.

The ITO on the PET substrate was scratched using a blade to form a “X”pattern such that four areas were formed which were not electricallyconnected, these were planar (or interdigited) electrodes. The size ofeach arm of the “X” was about 1.1 cm. The electrolyte paste wasdeposited onto 50′Ω/sq. ITO on polyester (ITO/PET) by doctor blade andheated at 120° C. for 15 minutes to form a white dry electrolyte 60microns. Choosing two opposite electrodes as the anode and two as thecathode 1.8 volts was applied to the cell and immediately the “X” regioncolored deep blue. When shorted the “X” region immediately bleach backto a white color. At 1.8 volts the peak current was 0.218 mA. The cellwas placed in an oven at 85° C. for 144 hours with no change in itscosmetics or electrochromic performance. Another device was made wherein the electrolyte PVP was substituted by 0.06 g of polypropylenecarbonate (everything else being the same) with a molecular weight of10,000. This device showed reversible coloration when powered at 1.8V.

EXAMPLE 29 All Printable Flexible Electrochromic Device

A spin coating solution of CLEVIOS pH 750 (obtained from HC StarckCompany) was prepared by adding 0.7 ml of dimethyl sulfoxide (DMSO) and0.0424 g of the surfactant Triton X to 15 g of CLEVIOS pH 750. Thesolution was stirred at room temperature for fifteen minutes prior touse. This solution was spin coated onto a rectangular piece of PET(1″×2″) at 500 rpm and dried in an oven at 110° C. for fifteen minutes.A printable electrochromic electrolyte was prepared by dissolving 0.5 gof polyurethane (PUL446-107) in 5 ml of tetrahydrofuran at roomtemperature. The mixture was stirred for 4 hours to insure completesolution. To this solution was added 0.78 ml of ionic liquid(1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and0.098 g (0.13M based on ionic liquid) of the electrochromic bridged dye1-(4 ferrocenylbutyl)-1′-methyl-4,4′ bipyridinium salt with1,1,1-trifluoro-N-[trifluoromethyl)sulfonyl]methanesulfonamide] orFc-Viologen imide dye. To this solution was added 0.40 g of titaniumdioxide (Ti-pure R960 from Dupont, coated with alumina and silica) and0.19 g of hygroscopic fumed silica (obtained from Aldrich Chemical Co,Milwaukee, Wis., product #38-126-8) which was mixed thoroughly for twohours. This electrolyte was deposited by doctor blade on the etched PETsubstrate pre-coated with conductive CLEVIOS coating. The electrolytedried at room temperature to give a thickness of 60 microns. Theelectrolyte was then coated by doctor blade with a carbon paste fromDuPont Electronics #8144 and cured at 110° C. for 20 minutes. Theelectrolyte layer was sandwiched between the Clevios and the carbonblack layers. At one edge of the substrate the layer with carbon blackand electrolyte was removed to a depth of 4 mm to expose the underlyingconductive CLEVIOS layer. A potential of 1.8 volts was applied acrossthis layer and the conductive carbon layer (the polarity at the carbonlayer was positive). The cell immediately turned deep blue and whenshorted bleached back to a white color. The peak current for colorationwas 1.5 mA/cm².

EXAMPLE 30 All Printable Flexible Electrochromic Device on BiodegradableSubstrate

A biodegradable substrate was obtained from McMaster-Carr of Santa-FeSprings, Calif. as a plate, product #8445T11. This plate was thick paperlike consistency and completely opaque. Conductive carbon paste fromDuPont Electronics #8144, was doctor bladed onto a this substrate andwas then dried at 110° C. for 15 minutes. This was coated with theelectrolyte described in Example 29 above and dried at room temperaturefor 15 minutes. These layers were then coated with a coating of PEDOT(Baytron P Jet HCV2 from HC Starck Company) by spin coating at 500 rpm.This coating was dried at 110° C. for 15 minutes. At one edge of thesubstrate the electrolyte and PEDOT layer was removed to a depth of 4 mmto reveal the underlying conductive carbon layer. A potential of 1.8volts was applied across this layer and the top PEDOT layer. Uponapplying the potential (top layer being negative) the cell immediatelycolored to a deep blue color and when the cell was shorted itimmediately bleached back to a white color.

EXAMPLE 31 All Printable Flexible Electrochromic Device on BiodegradableSubstrate

A cell was prepared using a biodegradable substrate as described inexample 30 above except that the carbon black layer was replaced byCLEVIOS. The CLEVIOS spin coating solution was prepared as described inExample 29 and was spin coated at 500 rpm and dried at 110° C. for 15minutes. This coating procedure was repeated a second time to obtainsufficient conductivity. To the finished device, when a potential of 1.8volts was applied across the cell (top layer being negative) it coloredwithin one second to a deep blue color and when shorted immediatelybleached to a white color. This procedure of coloration and bleachingcould be repeated.

EXAMPLE 32 All Printable Flexible Electrochromic Device on BiodegradablePlastic Substrate

The biodegradable substrate was a translucent polypropylene (PP) filmwith a biodegradable additive. This film was obtained from BloomerPlastics Inc, Bloomer, Wis. (product MC200PQ, 200 microns thick). Thefilm surface on one side had a matt finish and the other side had aglossy finish. Two devices were prepared on two different substrates,and in one case the device was formed by depositing the coatings on theglossy side and in the other on the matt side. A spin coating solutionof CLEVIOS pH 750 (obtained from HC Starck Company) was prepared byadding 0.7 ml of dimethyl sulfoxide (DMSO) and 0.0424 g of thesurfactant Triton X to 15 g of CLEVIOS pH 750. The solution was stirredat room temperature for fifteen minutes prior to use. This solution wasspin coated onto a rectangular piece of PP (1″×2″) at 500 rpm and driedin an oven at 110° C. for fifteen minutes. This process was repeated toincrease the thickness of the first electrode. This coating was thencoated over with the electrolyte described in Example 29 above and driedat room temperature for 15 minutes. These layers were then coated with atop electrode coating made out of PEDOT (Baytron P Jet HCV2 from HCStarck Company) by spin coating at 500 rpm. This coating was dried at110° C. for 15 minutes. A potential of 1.8 volts was applied across thetwo electrodes and the cell immediately colored a deep blue color andwhen the cell was shorted it immediately bleached back to a white color.The performance of both the devices was similar.

Display Construction, Integration with other Elements to Form Tags andLabels and their Applications

Inexpensive displays and indicators are required that may be producedfor product labels, office product labels, tickets, indicators attachedto sensors for food, drugs and biological/medical applications, giftcards from various stores and tags which are disposable or replacedperiodically. These displays may be irreversible or only have limitedcyclability. Irreversible means that the display or the indicator changethe state or show the information when they are activated the firsttime. This information may fade away after a few seconds or may last along time giving permanence to the image. Further many of the tags andlabels for such uses may not have an onboard power source and thus mayhave to be activated by power derived from other components located onthe same tag or the label. Such power may be derived from a radiofrequency coupling of an antenna on the tag, on optical coupling with asource or ambient light using a solar cell, or a sonar source, etc. Inall cases an electronic control unit (typically in the form of anintegrated chip) is introduced between the display and the power sourceto verify the source of activation, use a logic to arrive at a decisionif the display needs to be powered, and condition the signal toappropriately power the display to show the desired information. Thepower to activate the display is limited when the power is derived fromthe wireless signal. When radio frequency electronic chips are used tofurther power another component (e.g., a display) it is also calledradio frequency activation. Examples of these applications and some ofthe devices suggested for these may be found in U.S. Pat. No. 7,286,061(conditional access for antitheft of optical media) and patentapplications UA20080111675 (observable properties triggered uponinterrogation of RFIDs for tracking systems); UA20080100455 (a tag withan antenna and a chip showing a persistent image after interrogation forinventory control); UA20080170287 (a security device to provide a visualalert); UA20070114621 (wirelessly powered flexible tag); UA20070114365(antitheft optical shutter activated by RF); PCT applications WO08022972(EC indicator for product authentication) and WO08022966 (EC indicator).This invention discloses methods and ways on how such display/tags maybe configured to realize applications discussed in the aboveapplications.

The displays may be made in any way using any specific technology,however, EC displays, and particularly those formed by printingtechnology are preferred. Further, EC devices are able to react at lowpotentials (typically less than 3V) which means that these may bepowered directly from the low voltage output available from a variety ofchips, solar cells, batteries and capacitors. Those batteries arepreferred that are environmentally friendly, and more so for disposableproducts. For this reason alkaline or zinc air batteries are preferred.An advantage of EC displays is the ability to use batteries that output1.6V and lower. When the power is from RF, then it needs to berectified, as EC displays are DC devices. The rectification is builtwithin the intervening electronics between the display and the antenna.As discussed below this can be the part of the chip or it may be adiscrete element. In addition, these displays are preferably produced bya printing process to improve the economic viability.

The preferred display systems to be used for tags, product labels,payment cards, tickets, store gift cards, inventory control or to conveyalerts, product authentication, etc., combine a display and a wirelesscommunication system. For practical applications it is preferred toconstruct these as shown in FIG. 12. This figure shows the front(viewable side) and back of a label or a tag. This is formed preferablyon an opaque substrate 12 p (may be a plastic or a paper). The frontside shows a display 12 q which may be electrochromic and formed bysequential deposition of a bottom electrode 12 b, an electrolyte 12 cand the top electrode 12 a. Either of the two electrodes may bepatterned (not shown) or the bottom electrode may even comprise ofactive pixels, so that when the display is powered characters appear oronly parts color. The top electrode is a transparent conductor. Thedisplay is powered by connecting the two electrodes 12 d and 12 e to apower source or a driver. Depending on the display complexity andpixels, there may be several leads that will be connected to the driver,which may be a different chip and also connected to chip 12 n. However,use of additional chips decrease the economic viability for someapplications. In this case it is connected through vias in the substrateto 12 na and 12 nb pads of the chip 12 n which is located on the backside (the chip may be located on the front side, and then connected tothe antenna on the back side). It is advantageous to locate the antennaon the rear so that the front part of the tag may be used for othervisual information. The description of using front and back alsoincludes situations where one may print or place an antenna and thendeposit one or more layers or coatings to mask the antenna and thenprint or attach other visual information and the display on the otherside of these layer(s) or coating(s). The display and the antenna aresimilarly connected either through vias in the coating or by goingaround its edges. Further, the display may be energized by the powergenerated by the antenna once the chip confirms via the wirelesscommunication (as discussed later) that the display needs to beenergized. As an option, the chip may also be connected through the pads12 r through the vias to a solar cell 12 h located on the front side viathe terminals 12 k. This solar cell may provide additional power. As analternate, the solar cell may be replaced by a capacitor or a thin filmbattery, and these may be located either on the front or the back of thelabel. Any of the components, i.e., solar cell, chip, antenna displayand the interconnects may be formed by printing technology or one maypre-form these and then assemble them on a common substrate. For examplePolylC (Furth, Germany) is able to print transistors and othercircuitry, whereas Nanosolar (San Jose, Calif.) and Konarka Technologies(Lowell, Mass.) have demonstrated printed solar cells. Similarly,printed batteries are available from a number of sources, such as fromSolicore Inc (Lakeland, Fla.), Blue Spark Technologies (Westlake, Ohio)and Power Paper Ltd (Einat, Israel). For EC displays typically apreferred output voltage range is from about 1 to 3V. The chargecapacity of this will vary depending on the display size, powerconsumption and the number of cycles that need to be powered. Since mostof the displays for labels and tags will be powered rapidly from withina few seconds to some taking a few minutes or so. A battery with acharge exceeding 20 mA-min for every square cm of display would besufficient for a one time display. Further, this may be a secondarybattery that may be charged from the solar cell and/or the power derivedfrom the periodic coupling of the onboard antenna to an emitter. If asensor (not shown) is integrated with the display system this can beconnected to the chip 12 n using additional input/outputs from the chip(not shown), so that when the sensed output signal reaches a certainthreshold, the display can be activated. In addition, the power to thesensor may be provided by additional leads (not shown) from the powersource 12 h or this may be provided through its connectivity to thecontroller 12 n which receives the power from 12 h.

In order to keep the costs low, preferred printable batteries are formedout of zinc manganese dioxide or carbon zinc technology. These are lowcost materials and can be formulated into inks to be printed by screenprinting process or other printing methods. To retain a long termpermanence, those solar cells and batteries are preferred that compriseof ionic liquids in their electrolyte layer. Ionic liquid provides morepermanency or durability to the device as the liquid phase is notreadily lost to the atmosphere due to their low vapor pressure.Printable batteries using ionic liquids have been disclosed on paper(see Pushpraj, V. L., et al, Flexible energy storage devices based onnanocomposite paper, Proceedings of the National Academy of Sciences,vol 104 (34), p-13574 to 13577 (2007)), similarly, ionic liquideutectics are being increasingly used in the solar cells (MichaelGrätzel et al.; “Stable, High-Efficiency Ionic-Liquid-Based MesoscopicDye-Sensitized Solar Cells”; Small 2007, 3, No. 12, 2094-2102).Batteries and solar cells may be printed on line where the displays areproduced so that all of these may be printed on the same substrate, orthe other components can be prepared elsewhere and are integrated to thesubstrate with the display. The display substrate may be preprinted withthe conductive lines where the other printed components are placed (likea sticker) to align with the conductive pads and lines so thatelectrical connections are formed. All of these can then be protected bya layer of a curing resin that is deposited, a thermoplastic resin or bya lamination process to another film or substrate.

A cross-sectional view of the tag or the label described above (FIG. 12)is shown in FIG. 13. The substrate 13 p is shown with the optional solarcell (13 h) and a display (13 q) on one side and the antenna (13 m),optional battery 13 k and the controller chip 13 n on the other side.The connections between these elements are not shown. The connectors aremade by conductive lines on the same plane, conductive vias through thesubstrate, or by providing conductive paths around the substrate edges.There is an adhesive layer 13 s which is used to stick this label to aproduct package. Typically the antenna is not visible and may be quitelarge occupying the entire back side. There may be other printedinformation on the label (not shown) which is always visible. One mayprotect the display with an optional layer or a coating (e.g., UV curedcoating) on the top which protects all the elements. One may also make atag from this which has no adhesive backing. One may also laminateadditional layers either on the back or front for hiding some of theelements or protecting them and then applying an adhesive layer ifnecessary to bond this to the product or product package.

Such tags and displays have many applications. For example, a label maybe applied to a product that has an expiration date. For example, awireless system in the store may broadcast and communicate with theproduct tag once a day. During that communication, it checks for theinformation stored on the chip (in the tag) before instructing the chipto power the display element, and if the product has expired or is closeto its expiration date, it energizes the display and changes the colorof the pixel or displays new information. This provides a visual cue tothe store owner to remove this or for customers to visually identify theproduct if that has been put on sale. As an alternative, for expiredproducts the label may change color or display information when it isscanned at the checkout counter. As shown in FIG. 14, several indicatorsor displays (14 a, 14 b and 14 c) may be placed on one tag or a label,and each may be energized for different reasons. One scheme ofconnecting several displays on the same tag is to one chip (14 d) andone antenna (14 e) is shown in FIG. 14. To maintain concept clarity allof these have been shown on the same side. One may use multiple chipsand antennae on the same label. Some of these may correspond todifferent activation schemes, e.g., one or some may be activated by thestore system, and the others by customer using wireless devices such asa cell phone using “near field communication” (NFC) to confirm certainproduct characteristics. Other wireless technologies, such as Bluetooth,may also be used. Sometimes more than one technology may be used on thesame label, e.g., to communicate longer distances using blue tooth andshorter distances by NFC.

FIG. 15 shows another variation to assemble electrochromic displays. Asubstrate 15 a (paper, plastic, metal, etc.) is prepared with an antenna15 b, a wireless chip (e.g., an RF chip) 15 c, and one set of electrodes(back electrodes when opaque substrates are used). The patterned backelectrodes are shown as 15 e. These are connected to the chip usingconnectors (15 d) also deposited on the same substrate. 15 d may beoptionally isolated from coming in contact with the electrolyte 15 g bydepositing an insulating layer (not shown). All these components may beprepared discretely and then assembled, or preferably printed on thesubstrate (e.g., as by PolylC or technology from Kovio). The layer of ECelectrolyte 15 g is deposited (e.g. printed), followed on the patternedback electrode by a transparent conductor 15 f, e.g. using intrinsicallyconductive material such as PEDOT or a polymer filled with particulateconductors as discussed before. If upon application of power, theelectrochromic materials color near the top transparent electrode (asopposed to the bottom) then the pattern from the bottom electrode maybleed. This means the coloring EC material may spread at the topconductor and the edges may appear fuzzy. One way to overcome this is tocoat the top electrode in a pattern that is aligned with the bottomelectrode pattern. Another preferred way is to coat or print the top ofthe electrolyte with a patterned transparent electrically insulatingmaterial (shown optionally as 15 i) leaving non-coated areas that arealigned with the bottom electrode pattern. The transparent conductor isthen deposited uniformly on top of the patterned insulator. These layersor stack may be further encapsulated optionally by printing or coatinganother resin (shown as 15 p). In a reverse build one can start with asubstrate coated with conductive transparent conductor and then coatthis layer with a patterned insulating layer (e.g., UV or thermal cured)not covering those areas where the electrolyte would color, then coatingit with the electrolyte followed by a patterned conductive coating(typically opaque such as carbon black, or carbon layer followed by amore conductive layer). This coating is aligned with the patternedinsulting layer deposited earlier and then coated with an encapsulationlayer as long as the access to the tabs or lines to connect to thebottom and the top electrodes is still available. As mentioned earlier,solar cells, batteries or other components may also be added. The backelectrode may be conductors for passive displays or these may be pixelsfor active matrix display electrodes. As discussed earlier if activematrix is used, then it is important for the display to have a voltagethreshold (unless the connections to the pixels are masked by aninsulating layer) so that upon activation only the area above the pixelsis activated. The figure shows that the pixels are connected to eachother; however, these are usually connected to the chip. There may bemore than one chip, e.g., a chip connected to the antenna which mayprovide logic and memory for say authentication, and then this powersanother chip that drives the display i.e., the display pixels. In thisfigure no patterning is shown for the electrolyte and the top conductor,but that may also be changed. As an example, if a colored display isneeded, one may print the electrolyte in a way so that it is localizedon top of every pixel (though it is desired that these touch each other,or any space between is filled with any one of these or an inertelectrolyte, i.e. electrolyte without redox materials), and further, onemay use a set of every pixel with material that upon activation willchange to red, blue or green colors or any other required color set. Inaddition this also shows that the top conductor is brought in the sameplane as the substrate so that it is easy to connect that to the chip(the connection between the chip and the top conductor is not shown toconvey the principles in a simple way). A slight variation of thisconcept is shown in FIG. 16. Here as before the substrate 16 a with theantenna 16 b, chip 16 c and the pixels 16 e all connected by connectorsshown collectively as 16 d are laminated to another substrate 16 h thatis produced separately with a conductor 16 f and the EC electrolyte 16g. 16 d may be optionally isolated from coming in contact with theelectrolyte 16 g by depositing an insulating layer (not shown). Theconductor 16 f may be bonded to form a conductive path with pads on thesubstrate 16 a (not shown) to form the circuitry in the same plane. Asan example, substrate 16 a may be opaque (paper, metal foil, or anopaque plastic), where as 16 f and 16 h are transparent. Not shown inthis picture is a optional patterned transparent insulating layer tocontrol bleeding. Further all of these layers may be encapsulated byanother layer of polymeric material if desired. Several other methodsmay be used to make these displays using electronics on a back plane.For example U.S. Pat. No. 7,443,571 describes a process where anelectrooptic medium is pre-formed between conductive substrates alongwith an adhesive and a release layer. This medium is then assembled onto the back plane by removing the release layer and then adhered on tothe back plane. This may be done on a continuous web process. Thispatent and its teachings are incorporated herein in entirety. For ECdevices the electrolyte (usually the electrooptic medium itself) needsto adhere to the back plane as it needs to touch the conductiveelectrode. Thus if an EC medium is deposited on a substrate (typicallytransparent conductor coated polymeric film) along with a release layer,then it can be assembled using principles as described in the abovepatent but without using a distinctive adhesive layer. The electrolyteitself may be tacky or polymerizable after assembly. Further if the ECdevice is interdigited type then a top conducting electrode is notrequired, i.e., the electrolyte can be directly deposited on to apolymeric film and protected with a release layer, and at the time ofassembly on to the back plane, the release layer is removed and theelectrolyte contacted with the conductive pixels on the back plane.

FIGS. 14 and 15 show that the opposing electrodes are in differentplanes, However, using the concepts described in FIG. 9, one may placeall electrodes in the same plane, thus eliminating the need of anelectrode on a different substrate or even bringing down the topelectrode to a common plane to connect to the other elements of thesystem.

Although it is preferred that these tags be made by printing allcomponents in a single process line, in reality an integrative approachis preferred by some. This is because different companies are going tofocus on different components (e.g., electronic chips, power sources,power harvester, displays, antennas, etc), and also some of thematerials for these components may have to be handled in controlledatmospheres and may require processing conditions/equipment which mayinterfere with processing of other materials. Further, in some modulesthe precision required may be so high that specialized equipment may berequired which can push the capital cost of the entire line at the labelintegrator's facility. In one preferred approach the manufacturer ofthese labels and tags prints standard materials and integrates othercomponents that are produced by other suppliers or on a different lineand are provided on a roll or a sheet form which can be assembled in anautomatic equipment. As an example, the integrator starts with a roll ofa plastic material, paper or any desired stock “tag material”, andprints conductive lines that will be used to electrically connect allthe electronic modules. In addition the integrator may also printpictures, text, opaque layers and other information, and also laminateand apply adhesives that are needed on the tag to complete the product.The electronic modules comprising of a display, battery, solar cell,power harvester, antenna and the electronics may be bought from othersuppliers on a roll or sheets with a release layer which are then bondedand the electrical connections formed using electrically conductiveadhesives. All or some of these components may have been produced byprinting and are assembled on to the tag as if laying down stickers.Since there may be several closely spaced lines to be connected todifferent parts of the component, in this case it is preferred that thebond to the lines be made by “Z” conductive adhesive (ZCA) or alsocalled anisotropic conductive adhesive which is formed by dispersingisolated conductive particles in an adhesive so that they can couplewith conductive substrates through their thickness but not laterally.This material may be used only in selective area of the component or allover its bonding area. When the component is bonded to the tag material,then it is placed in a fashion so that the ZCA lines up with the desiredconductive lines so that the component is in communion with the system.ZCA allows an electrically conductive bond to be formed between thecomponent and the conductive lines or pads formed on the tag material.This adhesive may be thermoplastic adhesive or a thermoset adhesive. Thethermoset adhesive may be cured by heat or UV. This may be a pressuresensitive adhesive (e.g., pre-applied to the component), or it may bedispensed on the tag by the integrator during the process. Some sourcesof ZCAs are Molex® from Molex Switch Products (Lisle, Ill.), Loctite®products 3441 and 3446 from Henkel (Rocky Hill, Conn.), AdhesiveTransfer Tape 9703 and 9705 from 3M (St. Paul, Minn.), adhesives fromCreative Materials (Tyngsboro, Mass.) which may be supplied in sheetforms or can be partially cured (B-staged) on the components and thenfully cured after assembly. Use of ZCA is important only when there areclosely spaced lines which the printer or integrators equipment is notable to address individually due to the lack of precision. Thisprecision will vary from one printer to next. If for a given purpose theprinter can handle the precision then isotropic adhesives may be used,or these may be used for some connections and ZCA for the others in thesame product.

FIG. 17 shows the salient features of one of the preferred methods toform these tags or labels using a roll to roll process. The tags shownin this specific example are based on interdigited electrode design andthis tag will be formed by printing all the conductive paths, printingEC electrolyte and then assembling the other components. When finishedthe display can be viewed through the transparent or translucentsubstrate 171. 170 shows a tag that is part of a roll comprised of atransparent substrate 171. The tags are separated by perforations (172)along which these could be cut or torn later so as to physicallyseparate these. These perforations may also be formed after the completetag is formed. The display area is shown by four pair of electrodes,where one pair comprising electrodes 174 a and 174 b is labeled. Whenthe display is powered these electrodes power in opposite polarity,which causes the electrochromic material adjacent to one or both ofthese electrodes to color. If all the electrodes of this display arepowered four or seven sets of lines will be formed depending on thedistance between each set of electrodes. For example electrode 17 b canbe opposite polarity for both 174 a, and 174 c. As discussed earlier(FIG. 9), one may also form the alphabets using these principles. Alsoone may form a matrix of pixels where each pixel is independentlycontrolled to display any desired information. These may be active orpassive matrices. The passive electrodes in the display area of thisexample are formed using a transparent conductor. These transparentconductors could be printed or formed by uniformly coating the substrateand then selectively removing the coating to generate the desiredpattern. Typical resistivity of the transparent conductors is about 50to 2000 ohms/square. The lines connecting to these electrodes shown by173 a and 173 b may be formed of the same material or preferably from amaterial of high conductivity (to reduce power loss, resistancetypically less then about 10 ohms/sq and preferably less than 0.1ohms/square)) even if these are opaque, such as inks comprised of metallarge or nano particles. The same opaque inks are also used to form thepad areas such as 175 a (four of these only one labeled for clarity),175 b (four of these only one labeled for clarity), 176 a, 176 b, 177 aand 177 b. These pads are made so that they have large projected areaswith generous separation. This is because the label manufacturersusually do not have access to equipment to place components with highprecision. Typically, one should preferably design for tolerances ofabout ±50 μm, and more preferably greater than ±200 μm in order to makethem more process friendly for the label manufacturers. Some of theprintable carbon based opaque inks that can be used to form the linesand pads in this device or even back electrodes in any of the devicescan be obtained from Creative Materials as products 102-05F, 112-15,101-59, 118-43, 113-37, 110-03, 118-09 A/B, 105-43, 117-48 and 11841that range in conductivity from about 0.01 ohms/square/mil to about0.020 ohms/square/mil. Examples of carbon based inks from the samecompany are 104-18, 112-48, 108-46, 116-19, 110-04 and 119-28 withconductivity of about 20 to 75 ohms/square/mil. Similar materials mayalso be available from several other companies. One may use only silverinks to get high conductivity paths or electrodes or carbon if theconductivity is acceptable. In case one needs a high conductivity path,but lower electrochemical or chemical interaction with the electrolyte,one may use composite electrodes, i.e., the carbon electrodes touchingthe electrolyte or the reactive electrode and the silver in contact withthe carbon. The thickness of these may be from about 2 to 125 micronswhen dried or cured.

FIG. 18 shows an exploded view of how the other components can beintegrated on a substrate after forming the conductive lines and theelectrodes as was discussed in FIG. 17. The electrolyte 184 (assumingthis has the EC material) is deposited on top of the electrodes. Thebattery or solar cell or any other power source if used (183) isassembled so that its connector 183 b connects to the pads 187 a (or 177b as shown in FIG. 17). This connection is preferably established usingZCA. Similarly, the antenna 181 is connected using connectors 181 b andthey touch 186 a (or 176 a in FIG. 17). Finally the chip 182 is placedon the substrate so that its connectors 182 b touch the interior pads.These pads are shown more clearly in FIG. 17 (i.e., 175 a, 177 a, 175 band 176 b in order to electrically connect with the power source,antenna and all of the electrodes for the display. The sequence ofintegration may be any that is convenient. A preferred method is whereall or some of these components are provided as flexible stickers on aroll with a release layer, and at the assembly point the release layeris removed and these are bonded to the substrate. The conductors mayalso be provided on a roll (e.g., see thermal transfer printing fromCoding Products, Kalkaska, Mich.). The ZCA may be a part of the stickersor this may be dispensed. The sticker may encompass the connectors 181 band 183 b, and not be sticking out as shown in the figure. Also shown inFIG. 18 is another layer 185. This is an opaque layer with a window 185b that is deposited on the substrate to hide all of the components fromview other than the display. In addition this opaque layer can also beused to print any other information required for the product or use.This opaque layer may be deposited before printing the lines andelectrodes in FIG. 17, or this may also be a laminated layer which isdeposited on another substrate and then laminated to the label. A labelso formed with all the components is shown in FIG. 19. FIG. 20 shows theassembly from the top side and FIG. 20 b shows the same assembly fromthe bottom side. Any optional printed material on the opaque side is notshown. For a tag this may be completed by laminating this with anothersubstrate. The other substrate with the opaque layer and printed mattermay be provided on the assembly line with glue and a release layer, orthe glue may be deposited on line. For a label where it may be bonded toa product container or package, one can deposit an adhesive (curable orpressure sensitive with a release layer) on the side which has all thecomponents so that when the label is glued to the product package all ofthe components are hidden from the view. One may also laminate thisusing double sided adhesive with a pair of release layers where one ofthe release layers is removed in the process and the other is removedwhen the label is applied to the product. If need be the perforations asshown in the figures (e.g., see 172 in FIG. 17) may be formed at thisstage.

One of the important issue in this assembly is to realize that mostconvertors will not have access to form all components by printing andfurther will not have high precision equipment. For example amanufacturer, such as Kovio or PolylC, may provide printed electronicsstickers on a roll that may be used for the above assemblies.Alternatively, one may use chips on regular silicon or othersemiconductor substrates that are assembled with high precision onflexible substrates at a specialty shop so that the converts can userolls of these materials and use these to assemble the labels using lowprecision equipment. An advantage of silicon chips is their ability tohave more electronic features and memory and compatibility with a widevariety of global protocols, e.g., electronic product codes (EPC)standards, such as EPC Global Gen2 are promoted for RFID devices by GS1EPCglobal (GS1 EPCglobal is a subsidiary of GS1, US offices of GS1 arelocated in Lawrenceville, N.J.). FIG. 21 is an exploded view of theassembly showing a substrate 210 on which a conductive pattern 211 isprinted and a chip 212. The pattern end that is in contact with the chipwill have high precision and narrow lines. However, the pads 211 a thatwill eventually connect to the label are large and can be placed withlow precision during label assembly. A complete chip assembly on thesubstrate is shown in FIG. 21 b. FIG. 21 c shows a plan view of theassembly and magnified images of the chip connections to the printedpatterns is shown. These connections may also be formed by ZCA. The chipmay have a ball grid array type or solder bump type of connectors (notshown) that rest on the printed conductive lines 211 on the substrate.The precision of the chip assembly is usually finer than about 100microns, but preferably about ±20 microns or lower. These assemblies maybe provide on rolls of flexible substrate as discussed earlier andintegrated with the final product at the label manufacturer's facility.A close-up of the chip and the integration with printed lines shows thatall inputs and outputs (I/Os) on the chips are not being used. This maybe fine if a generic chip is used for a variety of uses and onlyspecific features of this may be used in the final product. One mayconnect all the I/Os to a printed pattern, and the label manufacturermay change printed pattern on the substrate of the label in a way to useor connect to only specific I/Os. This allows the label manufacturer toorder one type of chip on a flexible substrate which may be customizedto a different requirement from the end user of the label/tag product.In some cases one may be able to acquire partially integratedassemblies, e.g. a chip and an antenna assembled on a common substrateand the lines from the chip terminating as larger pads to avoid theissue of precision discussed above.

The above represents a flexible approach to make tags and labels byusing printing technology and integrating them with pre-formedcomponents, which may also have been manufactured by printingtechnology. For example, one converter may want to print the antennaalong with the conductive lines and decide that a display module needsto be bought and integrated with the label, while another may printconductive lines and a display and buy the other components. Anotherexample of this approach is also discussed below. Further, when severalcomponents are used to assemble them together it is highly preferredthat the composition of all the flexible substrates be similar. As anexample, one may use polyester for both the label stock and the othercomponents. This keeps their thermal expansion characteristics similarand provides products and labels with lower propensity to fail,particularly at the conductive joints. Further, ZCAs should be flexiblewithin the range of temperature the product is subjected to, for thelabels to work reliably.

A variation of the above concept is demonstrated where a display elementis acquired or formed on another line and then integrated with thelabel. FIG. 22 shows part of a roll of labels 220 with the usualperforation lines 222 to separate one label from the other. Also shownare conducting printed lines 223 a and 223 b which will connect to thedisplay via the pads 224 b and 224 a and to the chip substrate via 225 aand 225 b (for clarity only one of the four sets is labeled). The chipor the chip substrate will connect to the other components via pad sets226 and 227, as explained earlier in FIG. 17. This also shows a cut-out228 for mounting the display element which is fabricated offline orpurchased (in a flexible roll or as a stack) so that it can beintegrated. The display construction on a different substrate is shownin FIGS. 23, and 24. FIG. 23 shows a substrate 230 on which theconnecting pads 232 a and 232 b along with the electrodes 231 a and 231b are deposited (four of these, only one labeled for clarity). Theelectrodes and the connecting pads could be the same materials. Thedescription of materials and deposition processes is the same discussedearlier in FIG. 17. This could be a part of a roll to roll process wherethese are fabricated by printing. FIG. 24 a shows an exploded view whichshows the substrate with electrodes 240 (this is again for interdigitedelectrode configuration, although other configurations may also be used)and then an electrolyte layer 241 can be deposited by printing oranother process. The displayed is eventually viewed from the bottom sideof 240 as shown by an arrow. 242 is another flexible layer (transferconnection sheet) that is used to transfer the electrical connectionsfrom substrate 240 to 242 using ZCA. To show this transfer processclearly, FIG. 24 b shows another view of 242 where it is flipped over.This shows a sequence of features 243 a and 243 b which are formed byprinting electrically conductive materials (generally the same materials223 a and 223 b in FIG. 22 or 173 a and 173 b in FIG. 17). It is tothese features that 232 a and 232 b, shown in FIG. 23, connect to. FIG.24 c shows an assembled view of 240, 241 and 242 which is together shownas 245. This is also shown in 24 d where all the underlying layers areshown by dotted curves to show the connections. FIG. 25 shows theintegration of 220 (from FIG. 22) and 245 from FIG. 24 c or 24 d. FIG.25 a shows the top view showing 245 and 220 and FIG. 25 b shows the viewfrom the bottom and the cut out 228 (see FIG. 22) through which thedisplay 245 is visible. The visible parts of 243 a and 243 b (see FIG.24 c) connect with ZCA to 224 a and 224 b on the substrate 220. FIG. 26a shows a set of connections where 243 b on the “transfer connectionsheet” is used to electrically connect the display to the label or theelectronics (only one of eight such connections shown is labeled forclarity). The same top and bottom views respectively of the label whereall the connections are shown, are shown in FIGS. 26 a and 26 b. Asdiscussed earlier in FIGS. 17 through 21 other elements (electronics,antenna, power source, backing adhesive, opacifying layers, etc) can beintegrated to complete the label.

A particularly useful type of display for product labels, tickets, giftcards from various stores and tags which are disposable or replacedperiodically uses an irreversible EC technology, where after activation(preferably wireless) an electronic signal is applied to the display sothat the information is printed “forever” without the need of consumingadditional power in order to continue to display the information.Printed “forever” means relative to the product life which may be a dayto several years. A particularly preferred method of achieving this isby polymerizing a colorless or a differently colored monomer thatproduces a colored or a differently colored polymer as discussedearlier. The display may have a hidden message or a logo, which uponactivation reveals a visible code. This can be used for a prize, or showthat the product has expired, validation of the product, or may triggeranother event. As an example, a store gift card may have a display, andwhen it is activated, the amount put into the card is displayedpermanently. One may have receive several gift cards, and not know theamount unless they go to that store or one physically writes thatinformation on the card. Further, one may store this amount informationon the card or on a store network. Further, if the gift card has beenused, it is difficult for the user to check the residual amount if any.Thus the display can be activated in a sequence of events as theyhappen. When the card is bought by a customer it is activated and thetotal value available is displayed. Later as it is used, the informationis optionally updated to show the residual value as described below. Onepart of the display may be an alphanumeric or a numeric display andanother part may be represented as a bar or a strip as described below.Upon the card activation, the initial amount appears on the displaywhich is permanently shown. In addition to displaying the information onthe initial amount, may have a bar formed by with several irreversibleindividually addressable pixels, strung together in a line (e.g., like athermometer), and every time the card is used and some money consumed,the information is verified with the store network and/or theinformation on the card, and a proportional number of pixels changecolor giving a good estimate of the residual value. With increasing useas more of the funds on the card are used up, more of the pixels areactivated with each successive activation. This provides the user with avisual cue on the card value prior to using the card or even visitingthe store. A gift card based on such a system is shown in FIG. 27. Thecard is shown as 27 a, and one display or part of a display shows thefull amount of the card as $100 in 27 b. This card also shows that thevalue of the card remaining is $25 or 25%, shown as 27 c. Element 27 ccomprises of a bar with four pixels, but these can be in any numberdepending on the cost to produce this display and suitability of theapplication. Although the displays 27 b and 27 c are shown as separate,these are usually part of the same system with different windows or maybe integrated within the same window. In a similar way a ticket may beconfigured, where separate parts of the tickets are activated atdifferent times. For example, a part of the display is activated whenthe ticket is validated. Another part of the ticket is validated when anadditional item. e.g., food is bought, and yet another part of thedisplay on the ticket is activated when some prize is won, or differentparts are activated as the customer goes from one event to the other.Another application could be the price tags for various products in thestores, e.g. an apparel store. There may be a few spots (say 0.2 sq cmspots/pixels, about 1-4 in number) on the labels that may be activatedindependently. When promotions are done then any number of these spotsmay be activated, where one active spot may mean a certain discount andmore may mean a different discount/promotion. Since this can beimplemented store wide, even if an item is misplaced in the store, itstag can still convey its status, and these tags do not have to bemanually tagged for promotions. This activation may be permanent or fadeaway after some time so that if necessary this can be refreshed asnecessary (e.g. once a day). Another example may be folders where such adisplay is located (e.g., a hanging folder or a binder). When a user islooking for a specific folder, the user sends a wireless signal to theentire drawer full of such folders each having a specific electronicaddress. Only those folders that the user wants are activated (bydisplaying an image or by a change in color of a tag) for sufficienttime so that these are easily identified. For this reversible display ismore suitable. One may also combine displays with reversible andirreversible elements on a single product. As an example, one area ofthe folder label may be reversible and other irreversible. Theirreversible part of the label is activated when the folders need to beidentified for discarding or to be permanently moved to anotherlocation.

Another method may be used wherein the display of the product (e.g., acard) is reversible but has only a limited persistent time, i.e., oncethe display is activated, the information is displayed for a “shortwhile” and then fades away. “Short while” is again relative to theproduct life. This “short while” can be seconds, minutes or even severaldays. However, the last information displayed is stored in the chip(assembled or printed) on the card. This information may be readilydisplayed on the screen whenever the product is brought into an energyfield, which is preferably a wireless system. This does not alter theamount left on the card, or interact with any feature that would allowthe information from the card to be transmitted or altered. As anexample, the last displayed information may be displayed when theproduct is coupled to a cellular phone, a Blue Tooth device, a source oflight, or may be an activator designed to activate the display. Thisactivator may be a small universal display activator that is powered bybatteries or the mains.

FIG. 28 shows a method which can be used to create a series of bars thatcan be powered by a single connection. This means that each bar need notbe connected to the power supply separately. This would allow chips (orpower supplies) with few input/outputs (I/Os) to be used. This works tothe principle that as each bar is colored it continues to drain current,thus there would be a potential drop in powering that bar or pixel. Ifthe connections to the bars are configured so that the potential drop tocolor each bar is different, then depending upon the voltage applied bythe power supply, and the resistance configured, the bars willexperience different potentials. If the potential is above the coloringthreshold, the pixel colors, if not then it stays bleached, unless thevoltage is increased. Thus the voltage applied by the chip or the powersupply can be controlled by the logic/software This allows one todisplay information by coloring a number of bars but using fewer I/Os.Since each bar or pixel requires one pair of I/Os, this would mean thatthis allows selectively one or more than one pixel (or bar or segment)to be colored in the display, and uses less number of I/Os, i.e., thenumber of I/Os are less then the number of pixels which need to beaddressed independently. FIG. 28 a shows a cross-section of such adevice, where the section is taken through one of the pixels. 281 is asubstrate with a conductive coating 282. 282 may be a conductive patternthat is deposited by printing and only needs to be below 286 and 287 toconnect them electronically. 283 is an insulating layer (e.g., a polymerthat is curable or may be deposited by solvent evaporation) deposited bya print process. 286 is the electrolyte comprising anodic and cathodicredox materials where at least one of them is electrochromic. One mayhave additional EC layers below or above the electrolyte which are notshown. 284 is a conductive busbar that connects all the pixels and willbe described in more detail below. 285 is the top conductive electrodefor powering the EC device that is also connected to the busbar 284. 287is a conductive pad that is connected to the layer 282 to provide powerto the bottom electrode of the EC device. FIGS. 28 b through 28 fdescribe the complete layout of the device and its formation. One suchsequence is described; however, it will be evident from the descriptionbelow, that countless permutations are possible. A substrate 281 with aconductive coating 282 is utilized where an insulting layer 283 isdeposited as shown in FIG. 28 b. This also shows that four rectangularareas are left uncoated which will be used for depositing the ECmaterial/electrolyte (see 286 in FIG. 28 e). As shown in FIG. 28 c, aconductive pad 287 is then deposited touching the layer 282, to form thebottom connection to the device. FIG. 28 d shows addition of the busbarconnector for all pixels (284) being added. This can be added at thesame time as 287 and both formed from the same materials. Schematically,284 shows that its width between the pads for each successive pixeldecreases (compare 284 a and 284 b). This is showing the increasedresistance between the successive bars. These may even be coils ofconducting lines to achieve a specific resistance. It is preferred thatthis be formed by positive temperature coefficient materials (PTC) sothat with increasing temperature the resistance of these paths do notchange, so that the device performance can be maintained in a widetemperature range. The electrolyte 286 is then deposited as shown inFIG. 28 e. Finally the top electrode 205 is deposited that connects thebusbar 284 to the EC layer 286, as shown in FIG. 28 f Some of thenotable variations are a process where the EC layer is deposited afterforming the insulation layer, and then 287, 286 and 285 are deposited atthe same time and are made of the same material. One can also introduceresistance in the landing area of 285 shown as 285 a in FIG. 28 f When apotential is applied at terminals 285 c and 287, the voltage drop at theclosest pixel 288 a is least and increases as one goes towards 288 d(FIG. 28 f). If the voltage applied is such so that even afteraccounting for the voltage drop it is above the threshold for colorationat pixel 288 d, then all pixels (or bars will color). If the appliedvoltage is such that pixel 288 d experiences a potential less than thethreshold potential then it will not color, whereas if it is above thethreshold for 208 c then this and all the earlier ones i.e., 288 a and288 b will also color. This EC device may also be used as aninexpensive, printable voltage gage or voltmeter. One may printalongside of the bars showing the applied voltage depending on how manyof these pixels color.

One display system that can be implemented in a store warehouse or otherplaces is shown in FIG. 29. A wireless tag or a label 29 a is shown thatcomprises at least of a display, a chip and an antenna (other componentssuch as battery, solar cell, a capacitor or others may be added asdiscussed above). This could be a pricing tag or a product label. Acontrol bus with a wireless transceiver (29 b) runs through the shelf orthe area close to the wireless tag. A preferred distance between awireless emitter and the tag is in the range of 1 cm to 10 meters. Therecould be a number of transceivers that may be hard wired running alongthe length of a shelf. A number of these (e.g., 29 c and 29 d) maycommunicate with a central communication system either wirelessly orthey may be hard wired. Each one of these communicates with a specificdisplay, e.g., 29 d with 29 e, 29 b with 29 a, and 29 c with 29 frespectively and so on. These wireless transceivers can draw power fromthe mains, or may have sufficient battery power. This system may be usedto automatically update product pricing on a shelf, or indicate aspecial event, such as a sale. This may also be used to communicate withproduct labels to show a change in status, such as reduced pricing,expiration, etc. In the case of product labels each label, such as 29 ain FIG. 29, represents a bunch of labels placed on the packages ofidentical product. In addition, the chip on the product labels can alsoassist to communicate in terms of inventory levels remaining on theshelf. These are located so that as the product is handled, these do notwear out, whereas the tags may be replaced periodically. The wirelesstransceiver may also be a hand held device or be located on a mobilecart or a rail, which communicates with the wireless tags as itapproaches within the vicinity of communication/powering range. NFC mayalso be used at the check-out counter by the store scanning system,where the labels of expired items or for any other pre-determined reasonmay show a visual change so that an action may be taken at that point.

Another system is shown in FIG. 30. The wireless tag 30 a communicateswith a station 13 c, which in turn is in communication with a wirelesscontrol system 30 b. Station 30 c may be powered by mains or by abattery. As an example, 30 a may be a product label, 22 c may be acheckout station of a store which communicates to a central inventoryand product monitoring system 30 b. At the checkout the communicationbetween 30 a and 30 c and then between 30 c and 30 b establishes theproduct authenticity or makes sure that it is not expired or has notgone through storage conditions where it may not be suitable for thepurpose. In this example 30 b and 30 c may also be hard wired. Forexample see U.S. Pat. No. 7,286,061 to understand the transaction at asystems level where authenticity may be established by providing aunique key or code to each package by the manufacturer which is verifiedat the point of sale via the network. In this case through sensors orother means, the time/temperature/humidity history is stored on theproduct label 30 a. If the product is fine against a pre-definedcriterion, an indicator changes color or information and is displayed onthe tag 30 a to assure its status.

EXAMPLE 23 Display System with Wireless Activation

FIG. 31 shows schematics of a wireless system with a transmitter and areceiver. The receiver includes a display. This receiver is equivalentto a tag or a label. The display was made as described in Example 14.The receiver was a passive type system, i.e., it had no power sourceother than the power derived from the antenna when it coupled with thesignal from the emitting side. The transmitter was powered using a 12VDC power source. Impedance matching for the antennas was provided onboth sides. The physical separation between the two antennas was about 2cm. The filter on the transmitter side provided a stable DC signal whichwas about 1.2V. This was increased by the DC-DC booster to an outputvoltage of 2.3V. This voltage was measured without any load or when thedisplay was not connected. When the system was powered with the displayconnected, the output voltage dropped from 2.3 to 1.8V and the displaycolored. In an application the receiver will be packaged on a singlesubstrate with all or most components to be printed as describedearlier. This example only shows a powered passive wireless display.This does not show any intelligence on either side that can discriminateor make a decision on if the display must be powered when the system isenergized. A chip or a printable chip may be placed and connected to thecircuitry on both or only the receiver side as discussed earlier to addthis functionality.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrated andnot restrictive. The scope of the invention is, therefore, indicated bythe appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

The invention claimed is:
 1. An electrochromic (EC) device comprising apair of conducting electrodes and an electrolyte disposed between thepair of conducting electrodes, wherein (a) one of the said electrodes istransparent; and (b) the said device comprises a redox material which isa colorless monomer or a faintly colored monomer that polymerizes andcauses an irreversible change in the color of the said device when thesaid device is initially electrically activated.
 2. An electrochromic(EC) device as in claim 1 used for a display or an indicator.
 3. Anelectrochromic (EC) device as in claim 2 where the device is formed byprinting at least one of the electrodes or the electrolyte.
 4. Anelectrochromic (EC) device as in claim 1, where the said monomerpolymerizes to form a polymer when the device is activated by applying avoltage across the conducting electrodes, and the said polymer causes acolor change in the device.
 5. An electrochromic (EC) device as in claim1 wherein the electrolyte in the device further comprises of a secondredox material that is complimentary to the said redox monomer.
 6. Anelectrochromic (EC) device as in claim 5 wherein the electrolyte in thesaid device comprises the said monomer.
 7. An electrochromic (EC) deviceas in claim 5, where the said monomer polymerizes to form a polymer whenthe device is activated by applying a voltage across the conductingelectrodes, and the said polymer causes a color change in the device. 8.An electrochromic (EC) device comprises a pair of conducting electrodesand an electrolyte in contact with the pair of said conductingelectrodes, wherein (a) the said electrolyte comprises a redox materialwhich is a colorless monomer or a faintly colored monomer thatpolymerizes and deposits as a layer on one of the said electrodes whichcauses a change in the color of the said device when the said device isinitially electrically activated.
 9. An electrochromic (EC) device as inclaim 8, where the said monomer polymerizes to form a polymer when thedevice is activated by applying a voltage across the conductingelectrodes, and the said polymer causes a color change in the device.10. An electrochromic device as in claim 9, wherein the color change isirreversible.
 11. An electrochromic device as in claim 8, wherein thesaid opposing electrodes are in an interdigited pattern formed on one ofthe surfaces of a substrate.
 12. An electrochromic device as in claim11, wherein the conductive electrodes are formed on the said substrateby printing the said electrodes in the desired pattern or etching aconductive coating to form the electrodes in the desired pattern.
 13. Anelectrochromic device as in claim 11, wherein the substrate is aflexible transparent polymer.
 14. An electrochromic device as in claim11, wherein the electrolyte is a solid material.
 15. An electrochromicdevice as in claim 14, wherein the electrolyte is deposited by aprinting process.
 16. An electrochromic device as in claim 11, whereinthe electrolyte is protected from the environment using an additionallayer.
 17. An electrochromic device as in claim 8, wherein the twoopposing conductive electrodes are deposed in an interdigited pattern,and the electrolyte is deposited to contact the said electrodes, andwhen the said device is activated by applying a potential across thesaid electrodes it results in an appearance change which is notreversible.
 18. An electrochromic device as in claim 8, which is part ofa display system, wherein such display system is capable of wirelesscommunication.
 19. An electrochromic device as in claim 8, wherein theelectrolyte is a solid material.
 20. An electrochromic device as inclaim 8 which is a part of a display system, wherein such system islocated on a flexible substrate.
 21. An electrochromic device as inclaim 8 comprising a second redox material.
 22. An electrochromic deviceas in claim 21 wherein the second redox material is in the electrolyte.23. A display system comprising an electrochromic (EC) device, whereinthe said electrochromic device comprises (a) a redox monomer (a) andupon initial electrical activation of the said device, the said monomerpolymerizes resulting in an irreversible optical change so as to resultin a change of information being displayed.
 24. A display system as inclaim 23 wherein the EC device activation is irreversible.
 25. A displaysystem as in claim 23 wherein the said system is formed on a flexiblesubstrate.